I need some advice and after looking through a lot of old posts, I still need some help.
I am trying to refinish some red oak floors that are 50+ yrs old. They spent a long time under carpet and have some trouble spots, like dark splotches, areas without any finish, cupped boards, etc… I have learned that they are shellac and I don’t think they have any layers of wax on them. I am wondering if they have some sort of stain because in some spots that I had to repair and sand down to new wood, when I brushed on 2 coats of Zinzer Amber shellac it doesn’t quite match. Could that just be the age of the wood and not a stain?
Some more questions and info. The front two rooms had been previously refinished with Polyurethane and the color matches great where the two finishes meet. Would I be better off just using a drum sander (I think I would have to sand too long with a random orbital because of the cupped boards) and matching the front rooms? The Dark spots in the finish are kind of like scabs, I can use a putty knife to scrape some of it off but they go completely through the finish to the bare wood and I can only get them out by dabbing Denatured Alcohol on the spot, letting it soak in, and then wiping it vigorously. This of course leaves a ring of unfinished wood that I have tried to brush over to make it disappear, but cannot seem to make it blend in.
Also, I have been trying to find amber shellac in gallons but no one seems to carry it. Would I be better off mixing my own shellac (sources anyone?)? What did they do back in the 50’s? What kind of advice do you have for application?
I know it’s a lot but I feel overwhelmed right now…
Thanks,
Marc
Replies
Drum sanders really need skill to operate well. Gouges are the most common problem but you can also get wavyness and other problems caused by a lack of skill and experiance. Dark stains are most likely the result of water damage. a cat might have peed there or a plant was watered there etc..
If the wood is too badly cupped you may not be able to save it. You can only sand off about a 1/4 of an inch before you start exposing the spline or get the wood too thin so the spline splinters out..
Blending shellac IS SIMPLE IF YOU THIN IT ENOUGH.
Zinssler's sells shellac in gallons and most big box stores have it as well as some large paint stores.
Plastic er polyeruthane absolutely requires sanding to repair and you cannot sand part it has to be the whole floor.
To get amber from ultra blond you can mix some garnet flakes untill it matches.. make sure you add a lot of denatured alcohol or it becomes too thick to apply nicely. Flakes are more than 2times you follow the directions on the can. That plus it takes a lot longer to dry.
I commonly use 2 gallons of denatured alcohol to one gallon of Zinssler's for floors. it's really tough to skillfully apply shellac fast enough to keep a wet edge on it if mixed according to the directions on the can..
to get it to blend is it just a matter of putting on enough layers? Will it not make the existing layers darker?
The boards are not that cupped, just slightly. I would rather not sand if I don't have to.
I can find the clear in gallons but not Amber. Guess I might have to buy some flakes on-line. What are some good sources?I also need to match some aged pine trim. I have looked through the posts and watched Hand Applied Finishes: Coloring Wood with Jeff Jewitt who used nitric acid to age pine but I feel a little cautious about that method. Looking on knots, someone mentioned using tea. What would be the process if I was to use tea to "stain" pine and then finish it (probably with shellac).Thanks,
Marc
New shellac melts old shellac. That's what gives you invisable repairs.. that's also why you need to use thinned shellac so the denatured alcohol has enough time to melt into the old finish in order to blend.
When I've bought flakes I've purchased them locally from places that specialize in working with wood. I hate it because flakes are so much more expensive than gallons of Zinssler.Plus they take fussing with in order to get them fully mixed.. I used to use a morter and pedistal to crush them into powder but I've heard of using a coffee bean grinder to achieve the same thing (I don't know how well that works)
The other thing is too often the flakes have been sitting on a shelf for too long and that results in a sheelac that doesn't dry properly.
I've sanded my own floors with those square pad sanders (actually rectangel shaped, about 20"x24" )
My floors were a real mess because I had the planner set at slightly differant thickness everytime a spent a day making flooring. some of the differances in thickness were as much as a 1/4 inch. It took me about 6 hours to level out about 1000 sq.ft. (ask I'll give details about how to do it)
I didn't have any risk of sanding to the spline because I put the spline down towards the bottom and I Only planned one side so I had over 7/8ths thick wood with more than 1/2 inch to the spline.(that's what you can do when you make your own flooring from rough sawn lumber)
Edited 7/11/2009 11:59 am ET by frenchy
When applying shellac to a floor what is the best method? Lambs wool pad like for poly?
That works well and I wish I could remember to buy one..
I have an old barn paint'in brsush that I use but that's dumb the lambs wool applicator would get me off my knees. I have in the past when I forget the brush applied it with my T shirt.
The trick is don't paint it on, flood it on! Heck if I had a cotton mop I'd use that..
You need to just start over --sand and stain and refinish with poly for better wear. The dark stains could be pet urine through the carpet.
In the current housing slump, you may well find pro's who would jump at the chance to sand the floors at decent prices.
I have called a few places and I either get no return call or they don't refinish floors. I would rather do it myself anyway.
As for the dark spots they are all small, about the size of a pea, and the room was used as an office (read party room) so it could be alcohol.Thanks for the replies.
Marc
cank, about the size of a pea you say?is it strip flooring which was top nailed? because it sounds like water stains from the carpet being steam cleaned.this is very common ,also how do you know it is shellac? and are you sure it is not white or brown oak? because 50+ years ago both red oak and shellac are unlikely.Dan
Dan shellac was the most common finish for flooring untill post WW2 with the advent of new wonder plastics that were supposed to be better.
(they aren't but I digress)
The test is so easy that a caveman can do it!
My humble apologee to all cavemen <grin>
frenchy, 50 years ago is post WW2
yes! Your point?
and your point? other then insulting cavemen :)
Well I feel relatively secure since cavemen don't use computers <grin>
However if you bend over with a rag soaked with denatured alcohol and rub briskly you can tell if it's shellac in 30 seconds. No other floor finish is as easy to confirm.. (or remove)
oh and Glitza was formulated in the 1930's
Edited 7/15/2009 1:44 pm ET by woodguydan
I know that it wasn't the normal finish used on flooring untill well after WW2
It might be brown oak???
"is it strip flooring which was top nailed?" No I don't think so, it's 1.5" tongue and groove over 3/4 tongue and groove decking laid on a 45.Marc
drum sanders are really tricky, but there are floor sanders out there which have a series of random orbit sanders on the bottom of them. these are a little bit more foolproof to use than the old standby drums. that is if you've made a decision to sand through the poly.
I know what you are dealing with -- I have the same issues in my house. You pull up the carpet and find the floors in pretty good shape, except for a stain or two and worn finish in high traffic areas. What I did was spot sand where needed and apply a couple of coats of tung oil, followed by a couple of coats of shellac. I found the tung oil (after cleaning the floor very well) blended better. However, the tung oil will not provide any real protection, so you will have to cover it with something hard like shellac. I did the downstairs hall and the stairs to the second floor about 5 years ago and it is holding up pretty well. On the different colors in the wood, I had an area where there was clearly a color change in the wood caused by a carpet protecting part of the floor from sun. The sun exposed area was darker-- after about 6 years, the line has gone away as sun light has gotten to the area that was protected before. Good luck.
Dan, I wish I would have read your post earlier. I have just finished putting on 4 coats of thinned shellac. The spots are starting to blend but are still visible. I made the mistake of going across the grain the first coat and ended up with overlap lines that are also starting to blend after the 4th coat. I thinned the first coat 1.5-1 shellac which may have not been enough. I thinned the rest 2-1 and that seemed to "flow" better. I am using a lambs wool applicator on a pole and each coat goes on fast.
I am letting these coats dry overnight and plan on doing several more coats tomorrow. Here are a couple questions:
How long do I have before I need to use Shellac after I thin it?
When I clean the lambs wool applicator can I save that Denatured Alcohol to thin the next batch?
How can you tell when shellac is no longer useful? I bought some gallons of Zinzer amber that are 2 yrs and 3 mo old because those were the only two gallons left in the city.Thanks,
MarcOh, by the way, the floor is looking beautiful.
I think you are making a mess. Just my opinion. I think you have no idea whether it is shellac or not. It seems you are just finishing over the "problems". You need to sand the floors and start over.
Oh, and don't spill any water on your shellac floors, and be careful of whatever you use to "wash" them.
Gretchen
Edited 7/15/2009 9:00 pm ET by Gretchen
Gretchen
He does know it's shellac. The test is simple, if the finish melts with shellac it is shellac..
Second don't be so quick to fear water.. I had an airconditioner flood onto the floor which was shellacked about a month earlier. Giant puddle that had been there for many hours. I grabbed a towel and wiped it all up then fixed the A/C to stop the flooding. (I did this all by feel in the dark{I hadn't gotten lights hooked up in the billiard room yet}# In the morning I went up there expecting to find the floor all white..
OOPS!!!!!
The only indication of flooding was that area was dust free! I would estimate it had been wet at least 6 hours.
I know eventually shellac will turn white under water. I set a can down on one of my timbers and the sweat that ran off it caused a ring to form the next day. About a minute later I had the white off and first repair coat on.. Every time I dragged out the shellac I get another coat on and now you cannot find where I goofed.. If I could have stood the waiting. 15 minutes first coat, 30 minutes second coat, 1 hour third coat) with about 30 seconds to swipe some shellac across it for each coat I could have repaired it in 1 hour 46 minutes.. simply standing around for 1 hour and 45 minutes waiting for it to dry isn't my style though.
I would be concerned about shellac that old, but if sealed, you may be okay. Once thinned, you don't have much time with the mixture. I did not use amber shellac because I was using the tung oil to get the color right, and just wanted the hardness from the shellac. Water is not a real problem with shellac, don't let water sit for long periods, and make sure the surface is dry before you apply. Alcohol is a anothers matter -- it will dissolve shellac. If is has been more than a couple of hours and you don't have any surface problem showing, you are likely all right. The finishes you are likely to have in a 50 year old house are going to be oil based if there is a problem it will show up pretty quick. I don't pretend to be chemist and understand all the different types of finishes, so I usually make a point of testing in an out of the way area first. Don't let you have to sand and start over crowd get too you. If you floors are like mine, 90 percent of the area has a good finish that the carpet protected -- it is the high traffic areas and a few spots you have to worry about. You can spend a great deal of time working on matching those areas and still be time, work and money ahead.Dan Carroll
The other possibility (I have read through the posts, and added some ideas) is to lightly sand the floor and refinish with poly. It just might even out all your problems of matching stain, evening out the spots you have cleaned up, etc. You could even tint the poly to match. And floors are the ONLY place I have any use for poly, I would add.Gretchen
That would work certainly. I was under the impression that the idea was to avoid sanding the whole floor, even lightly. Given the dust and disruption and the noise I got SWMBO, I think the whole floor sanding option must be a last resort.Dan Carroll
But this would not be a huge sanding operation. It would need to be cleaned and even sanded with a pole sander. Wouldn't be a difficult clean up or a lot of dust.
And Frenchy, give it a rest. You are going on ignore because you are a one note and a complete bore. I have NOTHING against shellac--but there are other finishes in the world.
I am trying to help someone by offering a different possibility. He can make up his own mind.
Gretchen
Edited 7/16/2009 11:59 am ET by Gretchen
Gretchen,
I didn't think it was OK to use poly over shellac because of the wax?
Poly might be an option mainly because of availability. I am wondering about the soundness of the coats I put on yesterday, as they still leave marks when I walk on them. The Shellac was man. on 2/18/08.
I have managed to blend the spots however, by dabbing on shellac with a brush to each spot, letting it sit 15 sec or so, and then feathering it out.
Sanding will help with the adherence.Gretchen
I think I might end up going with poly because after 36 hours I can still leave a handprint or footprint in the shellac and it feels "soft".
It's too bad because I love the rich color.
The room I have done is only 10x12 and I still need to do about 750 sq ft in the rest of the house.
What is the best way to remove the shellac? Flood the floor with Denatured Alcohol and scrape it up with a floor scraper?
Or, will this floor eventually harden-up to where I can just leave it.
You mentioned tinting poly, is that something I would have to do or do some of the box stores do this?Thanks,
Marc
I'm guessing because I've never had a problem with soft shellac. But eventually the alcohol which is what is keeping it soft will work it's way out.
If you do decide to remove it it comes up with denatured alcohol and no you don't have to scrape.. simply get it wet and then wipe it up..
I stripped a 80 year old piano that way and it took me about 8 hours.. it would have taken me less time except I wanted to save the original decals so I protected the underside of the lid.
But you think it will harden up? I am getting frustrated and I am running out of time. I have until next Thurs. to have the rest of the floor completely finished. I have sent an email to zinsser to see what they recommend.
Thanks for your input.
Marc
Shellac that is soft after 36 hours is defective, it's not because the alcohol hasn't evaporated. And, it's certainly not the normal state for shellac, which is typically much harder than oil based varnish, especially polyurethane varnish. (That extreme hardness is actually why shellac is less scratch resistant than varnish.)
The most likely problem is that it is too old. Shellac has a very definate shelf life due to esterfication that occurs in accelerated fashion when mixed with alcohol. Shellac mixed yourself from flakes should be used in a couple of months--though it's worth testing for how it dries for months past that. The lower the cut, the faster the esterfication. Shellac purchased as a liquid has been processed to extend shelf life and a use by, or made on, date is on the package. Since you don't know about the storage conditions of those packages view the maximum dates very sceptically. Don't buy shellac even remotely close to its nominal expiration, and if you already own shellac more than several months old test it before using anyway.
I think you may well need to remove the shellac. DNA, and scraping and maroon 3-M pads are likely to be the best methods for removal.
Tinting poly, beyond a very slight amount, isn't a good idea. It becomes very difficult to apply evenly enough by hand, and doesn't dry quickly enough to be effectively sprayed--especially not in an "on-site" situation.
Or it might not even need to be tinted. Once the floor is prepared however he is going to do it, if he wets it, that will be the color when the clear varnish is applied. (I know you know this STeve, and many others). If that will even out all the places, then he'll be good to go with plain varnish.
At this point I am not sure WHAT is the next step!!Gretchen
That's also true. Any finish that "wets" the wood darkens it considerably. Then varnish with an amber tone darkens it a little, but only a little, more. He can get an excellent suggestion of the look of an oil based varnish just by wiping down with mineral spirits.
I re-read the thread, and I should have jumped in hard when 2 year 3 month old shellac was mentioned--I missed it. That's almost certainly the problem--that's got to be "out of date" for Amber shellac. That non-hardening shellac has got to be removed since it would be a weak link even if something would give the appearance sticking for a while.
At this point, unless a full sanding were done (which would be best), I'd avoid a polyurethane top coat just because of generalized adhesion issues. Remember the original shellac also contained wax.
A phenolic resin varnish would be a good choice if darkening is needed, and you wouldn't have to worry about wax in shellac if there were any residual. It would bevirtually as tough as, and in some respects tougher than, single part polyurethane varnish. He could still use fresh shellac--but that means only a few months old, and it really isn't a very good finish for floors. If there were any thought of applying polurethane varnish over the shellac it really should be dewaxed shellac. Seal Coat is the only liquid version sold by Zinsser. I'd use it anyway since dewaxed shellac is a bit more moisture resistant than shellac with wax.
Water isn't really the main hazard, or for that matter spilled drinks. The killer is household cleaners. Ammonia is a true solvent for shellac, and high alkali cleaners will also damage it. And this damage takes more than a wipe or two with a fresh coat of shellac to repair.
Steve,John WW, Gretchen:One slight disagreement on shellac. I have extensive oak floors finished by me with shellac. The first coat dries fast as can be, as everyone knows. However, it is a good idea to build up the film a bit (I know Frenchy disagrees, but I had a long correspondence with Zinsser technical about this four years ago before I started redoing floors with shellac). Anyway, as the film builds, drying time slows way down. In high traffic areas where I have three 3# coats, the third coat has taken as much as four DAYS to fully harden to the point that it wouldn't take a sock print if you walked over it. It is tricky that way. Zinsser says that FULL drying (which they call curing even though we all know it is an evaporative finish)can take 60 to 90 days, even with thinner coats. Of course, we all rub out shellac furniture finishes after a week or so.Lest anyone jump in and tell me that the thicker film will alligator or do something else awful, all I can say is that the only thing that has happened after four years is normal wear and tear -- which with shellac is very easy to touch up. I also got a couple of white patches where plants bases were less waterproof that we thought. Five minutes of fast passes with alcohol, a few minute wait, and all the white VANISHED. Lovely, eh?I love shellac on floors. there is nothing else that looks quite as nice. However, when it comes to drying, all rules are off with thick films.Cheers!Joe
Edited 7/17/2009 5:59 pm ET by Joe Sullivan
True, drying time lengthens, but the four coats here were of 1 lb. cut. That dries really fast--even the fourth coat. Three coats of 3 lb. cut would take longer, but Zinsser has an interest in making one think that shellac that takes three days to dry is OK. I can't quite believe really fresh shellac would take nearly so long.
I do suspect there is some sort of curing other that just evaporation going on, given the times I have observed shellac filled pores to "shrink" below the surface some time after they were initially leveled. Also note that esterfication continues, at a glacially slower pace, even with dry shellac--hence the deterioration and serious archival issues in preserving old shellac records.
Edited 7/17/2009 9:02 pm ET by SteveSchoene
Steve:I don't know why it happens, and I was pretty surprised the first and second times I did floors and left sock prints or chair leg prints a couple of days later, but it DOES happen,and with apparently fresh cans, within dating, and newly opened. The third and fourth times I did floors, it also happened, but I was not surprised. I now take it as a fact of nature.For furniture, I usually roll my own from flakes -- except for SealCoat which is good stuff and quite convenient.Cheers!Joe
Steve:I have heard of esterfication, but don't know what it means. Can you explain the process and effects?Joe
Joe, I tried using 2# cut and 3# cut shellac and like you it seemed to take forever to dry. Definately not overnight! That's why I used 1# cut on everything..
As for alligatoring it's going to take decades not a few years.
As I understand what really happens is the shellac tends to fold over as it shrinks and swells trapping dust into it. So I suspect if the floor is kept dust free it would take massively longer.
Frenchy:
Kids, dogs, cats -- country life -- I'm not sure I'd know dust free if I saw it.Joe
Joe,There is something wrong with any shellac of ANY number of coats that takes days to harden and is soft enough the take an imprint of anything during that time.Period.Despite advice to the contrary from Zinser.Mixed shellac can become unusable in the bottle over time and flakes can also undergo esterification changes that make them very difficult to dissolve. Dissolved shellac that does not dry hard in a few hours, or flakes that don't completely dissolve in 24 hours are not suitable for use. It's just that simple.Good, fresh shellac dries so fast it is difficult to control for most people. That's a common complaint and unjustified rap against it, until the finisher gets enough experience to eliminate brush marks or to learn to spray it. There is just no reason at all to use old shellac when fresh stuff is so readily available and has far - far superior qualities in every respect.I always spray. I have never had a problem with multiple coats. Yes, drying time is a little longer as the film builds, but just a little. It is NOT a matter of days. If a film of shellac, even at the 4th or 5th coat is not absolutely dry to the touch in 2 hours and extremely hard (NO possibility of taking ANY kind of imprint), it's bad. I don't level sand until the next day, but my applications are dry and HARD by the time I've finished cleaning my equipment.I always mix from flakes but fresh Zinser shellac should do the same thing. Zinser is in business to put dissolved shellac on shelves for long periods. They have succeeded in prolonging shellac's shelf life. But they know that much of their product is going unsold for too long and have probably found that marginal solutions, that stay soft for days will eventually get harder. (But they never achieve the quality of fresh shellac). So they give that advice, to protect their product. That doesn't mean you have to go with it.Rich
Well, OK, be that as it may, very few people are going to mix fresh shellac to be applied to a few hundred feet of flooring. they are going to go to the Borg and buy Bullseye, just as I did -- and I have several variations of flakes and am quite familiar with mixing them.So, regardless of whether it is Zinsser's fault or a characteristic of shellac, anyone who is going to finish floors with shellac needs to know that there is a good chance that the later coats will take a long time to dry.Joe
Joe,The Bulls Eye product, within its truly "fresh" period, is an excellent product. It performs as well as freshly-dissolved flakes.You are right that that "very few people" are going to mix shellac. Whether the Borg's supply of shellac is fresh is hard to say. There's probably a great deal of variation from store to store about how much they move in a several-month period.But very few people are ever going to try to finish a floor either. THAT is not something most wood workers are ever going to do. As a matter of fact, finishing a floor requires quite a different skill set than even an experienced furniture finisher acquires. And part of that knowledge includes good understanding of the materials to be used. For someone who doesn't do it regularly, and isn't buying shellac regularly from a dependable supplier, and continually satisfied with the way the material handles, shellac in the can, from any store is "mystery liquid."No other can on the shelf has an expiration date. It needs to be tested a bit before relying on it. A few coats on a piece of scrap will do it. (I'll bet you'll test the next time you have the urge to do floor finishing!) If the first coat isn't ready (dry and hard) for the next in 30-45 minutes or if you can't put 3 coats on, over the course of a half day and have it dry and hard an hour after the last, don't use it.I've never had a shellac film perform like the soft finish you experienced on your floor. I don't recall any others here having quite that bad a problem either. So you're the forum expert on that!Rich
Look, Rich, I'm not arguing here, just reporting. In each of the four cases that I did floors (three myself, one with a flooring crew working while I directed and watched), we used two to three coats of uncut Bullseye. In every case, the product was within date, and freshly opened. In EACH case, the first coat dried within 45 minutes. In EACH case, the second coat took longer. In EACH case, the third coat took days to reach a hardness that would withstand chair legs, and in EACH case, there were spots that would take sock prints for up to three days.Now, I use shellac in different cuts on furniture, tool handles and other objects quite a few times a year. I never have these drying times, either with Bullseye or with my own mixed from flakes. I usually wait about a week before rub-out and waxing of a final coat of furniture shellac -- as does Peter Gedrys. But in terms of handling the stuff, sanding to powder, normally a couple of hours and Bob's your mother's brother. The only problem I ever have is pilling on the sandpaper.So, what's different? Two things: a) on floors, we used the uncut 3# Bullseye, and put it on thickly thus giving a much thicker film than I would ever use on furniture; b) chair and table legs put a lot more stress on a finish than anything I'd dream of doing to furniture.If I were to guess, and this is a pure, rank guess, I'd guess that the thick film dries more slowly due to solvent entrapment as the top evaporates first and gets thicker and tougher. We never have this problem with furniture, because we never approach that thickness of film. Joe
Joe,I wasn't arguing either.Next time you apply multiple coats of 3# cut shellac to a floor, it might be interesting to try dissolving (fresh) flakes and see how that works.I must admit I don't apply (spray) shellac much more concentrated than a 2# cut. I don't measure precisely, but my solution is somewhere between a 1-1/2# to 2# cut. I'll go buy some Bullseye from HD and apply it with a brush at full strength to see what I get.Rich
Wow, lost of stuff here.
First off, Steve, I haven't used the 2 yr 3 mo old shellac... yet (read, probably won't). That was purchased but not used. I am testing that out today on some unused flooring. The Shellac I used for the first two coats was within Zinssers Shelf life, 2/18/08. What about this for the extended drying time. If I put 4 coats over an old floor that already had 4 coats of say 3# cut, would that considerably lengthen drying time. The floor was not worn at all, it just had those tiny spots that I had to repair, so it had plenty of finish on it already. Maybe I should have "filled" the spots that I stripped and then laid down one "rejuvenating" coat.Another question, if the finish is still curing (evaporating), is it safe to use it as my 1 yr old son's room? I have 3 kids and we are trying to work out sleeping arrangements and his room needed to be done for the "switch". Even if I strip the floor, I will probably have to do that after I re-finish the rest of the house.When I called every paint store in the area just about all of them said it was something they have not had requests for for a long, long time and they didn't have any. Only one place said they had 1 Gal from Dec '07 left over from a custom order job where a contractor used twelve gal. to finish the interior of a trendy eatery downtown.
I even found some at HD from '05. To all
I have been ventilating with one fan in the window in another room (this old ranch style house has crank windows but storm windows have been installed and caulked into place) and the only windows that open are in the new master bedroom that I just finished (OK, so I'm not done with the face-frames for the closet shelving, or the vanity, or the pocket door, or the... but we can sleep in there!). I put another fan in the doorway of the room I have been working which pulls the air out of the room and directs it to the room with the open window. This seems to keep all of the fumes from the rest of the house except when I forgot to turn off the AC and the return air pulled some fumes back in. I am also wearing a 8577 NIOSH P95 mask.On a different finishing note, I have been staining some birch for our closet system using minwax oil based stain and using the same type of mask. After staining for a while, my eyes are swollen and itchy. Not real bad, but noticeably. I do have ventilation, a large exhaust fan at the peak of the roof.Anyone else have this problem, and is there an easy(cheap) solution?Rod
I had thought of using a coat of dewaxed and then poly but didn't know if the the old finish would "pull" trough that new layer. Anyone have suggestions for this method? Would I use it uncut or cut it to 1# or 2#?Thanks for all the responses.
Marc
So, the shellac you had problems with was 1 yr and about 4 months old, and not the stuff a year older. That's still plenty old in my book, and could be functionally over the hill, especially when you don't know how the product had been stored. In an air conditioned store is one thing, in a warm warehouse is quite another. Frankly, lots of folks caution that for many purposes the standards Zinsser uses to set the shelf life may not be strict enough.
Applying new shellac over old will have some additional impact on lengthening drying time as the alcohol in the new shellac does dissolve some of the old shellac.
Another aspect that hasn't been mentioned is how the surface was cleaned of twenty years (or whatever) worth of grime. That can also impact how shellac and other finishes cure. The surface needs to be well cleaned. I'd start with TSP in a water solution, cleaning thoroughly, but by no means flooding or soaking the wood. Then cleaning with mineral spirits to remove oily dirt. Light sanding doesnt' remove such grime, though full scale pro-type sanding gets deep enough to remove it mechanically.
The 8577 P95 respirator is a mostly particulate mask I think, though with some "relief for nuisance levels of organic vapors". I don't really know enough to say whether that implies any protection from the alcohol vapors of shellac. The 3M data sheet I read for the mask is pretty ambiquous about the vapors protection. And, as you could tell from the stain example, you know protection isn't very much. I think I'd uncaulk a storm window or two so that you at least get some cross ventilation
As far as sleeping quarters for a 1 yr. old, if I could walk directly into a room, after spending an hour or so outside, and could tell that there had been shellac used I wouldn't put the child there. That's not based on science. But this is something better safe than sorry.
But, your question is what to do. Shellac that isn't hard, really hard has be be removed before anything else. Varnish has toxicity problems more or less equivalent to shellac with solvents that children in particular shouldn't be breathing for extended period so that's not a clear cut choice. Even rooms finished with waterborne floor finishes such as Bona Kemi Mega or Traffic shouldn't be slept in immediately, though rooms are occupiable sooner than with oil-based varnish.
Floors are challenging. Even shellac, which ought to be the easiest to apply choice, hasn't turned out that way at all, and isn't the most wonderful of finishes in the end, though not all quarters agree. Non-poly varnish would be likely about the best choice over cleaned and lightly sanded floors that retain some old finish in sound condition.. Polyurethane varnish is more persnickety about the substrate and I would avoid it unless the full scale sanding were done first. Done professionally, the whole process would be done most quickly with waterborne two part floor finishes, since the recoat time is shorter.
Thanks Steve.
From some searching prior to all this I just used DNA to clean the floor. I would clean an area then turn to a clean piece of rag and clean some more. That seemed to get it pretty clean, maybe not clean enough though.If I sand the floor down I will use one of the Clarke EZ-Sand orbital floor sander. I used one when I finished the new floor in the addition and it was pretty easy to use. With shellac though, what is the best method to keep the sandpaper from clogging up?I guess I should mention also that I am not going for immaculate floors. I would like the floor to retain some of that lived-in feel, rather than look like brand new construction. I think that is part of the charm of living in a older home. I don't think I would of had all these questions though if the first room that I did would have cured properly and the supply of shellac was not so spotty. Mixing my own shellac is cost prohibitive but maybe after I go to the crater of diamonds in a few weeks, I'll be able to afford to buy a new house and not worry about these floors...Marc
Moreberries is right. A good standard cleaning, followed by a light screening and then a coat of de-waxed shellac should be adequate prep for most floor finishes. I am not a floor pro, but I have done eight of them now, four with shellac, one with a discontinued Zinsser product called Target, one with waterborn poly, and two with oil-based varnish.Two of these were newly laid wood, while the rest were refinishing jobs.Especially if shellac is to be your topcoat, you need nod actually sand (as opposed to screening) unless you have other problems like cupping.
cank,
sanding shellac = clogged sanding disks. Wipe off, don't sand!
I would expect a 1lb even coat of dewaxed would suffice to seal off the floor.... Shellac is well known for sealing and adhering in very difficult situations....however without rereading the entire thread I'd expect your problem actually lies in the initial floor prep.....assuming you first thoroughly tested the floor to insure it is indeed shellac and sampled your "new" finish on clean new wood for drying etc.......When I was doing wood floor recoats (gyms, schools, courts and houses) I would carefully clean and abrade the floor first. On a house I'd wet scrub with a floor machine with strong detergent then rinse and dry. Then abrade with screen disks (again using a floor machine) then dust or vac and tack(clean towels slightly moist with thinner).....The screen disk (depending on the grit used) will nearly remove all existing surface finish but doesn't sand or penetrate the wood much..almost idiot proof if you understand floor machine basics. The surface is now smooth and very clean with all existing surface flaws and existing finish wear and tear damage gone. That said any wood floor refinishing without sanding to bare wood has a higher risk of failure..... Too many variables. Rod
I'm worse than you man, I'm living in the house as I build it.. dust, woodshavings, shellac droppings, etc..,Add to the list you have..
It's worse than most because I started with roughsawn wood and have to mill everything and then shape it. Then sand it and cut it to fit etc..
I've still got over 10,000 bd.ft. to turn into things. there is no way I can seal off one room etc.. and contain the dust so I just let'er fly
Has anyone used fresh shellac? I have brush applied 3-4 (at least) coats of 2 lb. cut in an afternoon, and have had it sand to powder the next morning.
If the shellac is still soft it was too old and it will need to be removed, normally it takes only minutes to harden, much faster than any other type of finish. In fact, very fast drying is one of the great advantages to using shellac. One thing to pay attention to: alcohol fumes are explosively flammable and you will be putting a lot of alcohol in the air when you strip the old shellac off. Use lots of ventilation and watch out for sources of ignition including in the basement where the fumes may settle. Also, the types of alcohol used for shellac are toxic and readily absorbed through the skin, you will need to use gloves that the alcohol won't penetrate. Latex or rubber will offer almost no protection, butyl or nitrile are better. Get the heavy thick gloves not the disposables which offer little protection and are too easily torn.John White
Shop Manager for FWW Magazine, 1998-2007
Edited 7/17/2009 4:46 pm ET by JohnWW
John I'm sorry but the information about how explosive denatured alcohol is wrong.. First alcohol doesn't explode.. it burns!
But more important Here's why.. the standard way to put out an alcohol fire is to toss water on it. That dilutes the alcohol to the point where it won't ignite no matter what..
We are in a period where most areas are extremely humid thereby achieving that same mix of water (in the humidity) to alcohol vapor.
IN addition alcohol is extremely fussy to ignite. It requires a narrow window of fuel to air ration of about 7 to 1. At 9 to 1 it won't ignite and at 5 to 1 it won't ignite either. At either extreme the combination has to be exactly perfect with a strong spark to ignite.. Now add humidity back in and you see how difficult ignition would be..
When you add in how quickly alcohol vaporizes and disperses unlike other volatile liquids there is a very narrow and tiny window whereby alcohol will ignite..
I'll grant that a level of care is required but unlike most other "thinners" etc. alcohol is much safer..
There are plenty of cases of alcohol fires. The real risk is that it is an almost colorless flame--perhaps a blue tinge. It could ignite across the room, or in the basement and travel unnoticed. Ventilation, and shutting off pilot lights, is a good, ie really good idea.
I also recommend a mostly ethanol DNA. Many brands are now about half methanol Sunnyside DNA was one brand with a high ethanol content last I looked.
I haven't tried ethanol alcohol yet. I still have several drums of methanol alcohol to use since they are now too old to use in the race car. ( I paid only aout 30 cents a gallon in bulk)
Yes there have been alcohol fires and you are correct that they burn with a nearly invisable flame. In fact any smoke etc.. is given off from other things on fire..
However the statement I gave about the difficulty of ignition is valid. Race cars using alcohol are extremely tough to start in spite of the massive magneto's usually used. That's why they are normally started with gasolene squirted into the throats of the injectors or carbs.. starting race cars on the starter is too hard with pure alcohol because too much floods them and too little won't ignite them..
Methanol dissolves shellac readily, and evaporates faster than ethanol but I sure wouldn't use it with light cuts of shellac in the volumes used on floors, at least not without full supply respirators. That stuff can make you blind. At least the antedote for methanol is ethanol, so a good glass of spirits is recommended AFTER the job is done.
When I do the floors I simply open a window or 6. Smaller stuff (unless I spray) I don't bother because the house is 5500 sq.ft. and a quart or 2 of alcohol isn't enough to affect me. With it's rate of evaporation in minutes you can't even smell it..
I've used Fresh shellac and when I use them in the 2 & 3# cuts it takes forever to dry.. I can apply 3- 1 pound cuts inside of 2 hours and have them dry so I don't see how I save any thing (except alcohol) by appyling one 3# cut that takes forever to dry..
Frenchy,Thanks, good information to have.John W.
Gretchen what is your objection to shellac?
The finest violins and antiques prefer the depth and richness of shellac over the plastic look of poly. Shellac has been the finish of choice for many many centuries
Shellac is a remarkably tough and durable finish, (my 150 pound dog hasn't ruined it yet 4 years after it was applied to the floor where he lays and runs around barking, jumping etc.. (what's worse he refuses to clip his claws) <grin> as far as durable over at Fine Home Building a guy wanted to know how to remove 80 year old shellac. He'd been sanding for a while and it didn't seem to come up very well. (You don't sand you wipe it up with denatured alcohol)
It's safe, we've been eating shellac on pills and candy all of our lives..
It's insanely easy, its fast drying and virtually odorless within a few minutes of application. It's biodegradable and renewable plus it is a naturally occuring item unlike poly which comes straight out of a chemestry lab..
It's two weaknesses? booze and amonia. With booze, what are you doing wasting single malt scotch by pouring it on the floor anyway? <grin>
OK let's say you did. If that scotch were 100 proof (and you drink it neat) that means it's 50% water.. so you still have time to wipe it up damage free. A mixed drink beer or wine all give you even more time..
As for amonia ,
It's not hard to avoid something.. You do it all the time.. You don't wash your dishes in motor oil do you? you don't shampoo your hair with soda pop do you? So don't clean shellac with amonia!
Besides with shellac it's so easy to repair you might want to do it for your guests at a party.. (just remember to say abra cadabra at the start and Ta da when you are finished) <grin>
With Poly however, you have to sand the whole floor because poly doesn't do invisable repairs like shellac does.
Putting poly over old shellac (or remaining shellac residue) may not be a good idea....the old shellac is probably not "dewaxed" and the poly may not dry.....regretably I found out the hard way on a customers floor. Putting a barrier coat of dewaxed shellac and then the poly would work however. Rod
Since I have a never ending house to finish and I'm committed to using shellac on all my surfaces I keep a open gallon of shellac finish all the time.. it may be weeks or a month before I apply some more and if so I simply add a lot of denatured alcohol to it and keep at it.
I haven't had a single problem in more than 4 years with that system.
shellac seems to forgive the careless!
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