NEW! Faster Search Option

Loading

Urethane over linseed oil

MarkRD's picture

I really love the effect of diluted (with mineral spirits) linseed oil. It gives wood wonderful "depth" and brings out the grain in light woods.

However, the first coat of urethane seems to take forever to dry. For example last night I urethaned a project with linseed oil (oak, birch plywood, walnut) and another piece of oak (some molding).

The plain oak was dry to the touch this morning.

The linseed oiled oak was still quite tacky. I move the project to a very warm location that has helped but I'm going to have to sand out the extra dust and recoat :-( (not to mention the extra waiting time. I'm almost done with this project...)

The linseed oil coating was dry to the touch before urethaning.

Is there a better diluting agent than mineral spirts (should I use something else?) I'm using a 50/50 mix, should I cut the spirts down 75/25? or up?

I'm using urethane because I need a pretty tough finish - it's a bow case (target archery) for my son's equipment - so it will travel a bit.
Here's a pre-finished picture: http://www.pbase.com/durrenm/image/41064514.jpg

Any advice?

Thanks,
Mark

Measure it with a micrometer, mark it with chalk, cut it with an ax.


Edited 3/24/2005 1:46 pm ET by Mark

Measure it with a Micrometer,
Mark it with Chalk,
Cut it with an Ax.

Visit my woodworking blog Dust Maker
Ardito's picture

(post #107580, reply #1 of 24)

Nice looking bow case! 


As far as the Linseed Oil is concerned...I assume you mean to say you are using "Boiled Linseed Oil", because if you are using real linseed oil it will never dry.  I also really like the effects of Boiled Linseed Oil on the grain.  I have also used a 1:1 ratio with Mineral Spirits and achieved great results.  What kind of  time frame did you leave between your Linseed Oil and Urethane?  The reason your Urethane coat is taking so long to dry/cure is because the Boiled Linseed Oil is still "gassing off" some fumes and not fully cured yet.  Here are some guidelines I like to follow:


1.  Finishing environment should be above 60 degrees.
2.  I like to leave anywhere from 3 to 7 days drying time for the Boiled Linseed Oil
3.  If you don't have that kind of time between Linseed Oil and your topcoat, I will use a seal coat of dewaxed blonde shellac and that will seal up the BLO.
4.  If you do use the shellac approach, you will need 24 hours drying time of the BLO before you can use the shellac, and you must use dewaxed shellac.  Urethane will never bond to regular shellac.


One other thing...you could try and use Naptha instead of Mineral Spirits.  The Naptha "flashes" faster then the Mineral Spirits.


Cheers!
Dark Magneto

MarkRD's picture

(post #107580, reply #2 of 24)

Thanks,
Yes it's boiled linseed oil.

My shop hovers around 60 maybe slightly above. I'll just have to get heat. Hon, can I spend more money in the shop...

I finished the oil monday night and did the urethane Wed night. Just 2 days ... Ok I'll give it more time next time. The good news is that the heat is speeding up the process. I'm hoping to finsh the whole project by saturday so my son can take the box to class.

Naptha? Hmm never looked for it so I wonder if I can get it at the local hardware store or HomeDepot.

When you say "flashpoint" I'm assuming you me it has a lower vapor pressure (it evaporates easier/quicker than mineral spirits).

FYI, this is my second case and I learned a lot from the first one. I use the first one for my archery equipment. But I've learned so much, that I want to rebuild mine :-)

Mark


Measure it with a micrometer, mark it with chalk, cut it with an ax.

Measure it with a Micrometer,
Mark it with Chalk,
Cut it with an Ax.

Visit my woodworking blog Dust Maker
Ardito's picture

(post #107580, reply #3 of 24)

Mark,


Yeah, you can find Naptha no problem at any Home Depot/Lowes/ etc.


I would definitely let the BLO cure for longer than 2 days before I move to the Urethane step.  If your shop is around 60 than I would let it sit for a week before I went to Urethane. 


Just think about all the hard work and effort you put into building this case, you would hate to "rush" the very last step.  The key to successful finishing in the home shop is patience.  Most home shops are not setup with spray equipment and can not spray some of the professional products.  We then have to use wipe-on or brush techniques which will require patience between each step. 


Post some pics of the bow case when it is done!  Looks great so far!!!


Cheers!
Dark Magneto


 

Ardito's picture

(post #107580, reply #4 of 24)

Mark,


One quick question...did you use any plans for this case?  How did you do that banding on the case?  Did you construct the case and then saw it open?


Cheers!
Dark Magneto


 

MarkRD's picture

(post #107580, reply #5 of 24)

The plans come from my head. I sized it based on my son's equipment.

1. I build two oak frames (top and bottom) out of 3/4 x 3/4" white (or red oak) The oak has been planed square

2. I miter the pieces on the "chop" saw.

3. I built a jig to cut the spline slots on the router with a router biscuit slot cutter (MLCS sells them)

4. Made the biscuits out of black walnut (resaw close to the right thickness on the bandsaw, then on the planer to just over the right thickness (dial calipers come in handy here)

5. I sand the splines to fit - snug because they don't expand like regular biscuits. I also cut them on a curve (band saw) so they will fit all the back into the slot (this is important for later)

5. I use a set-it square and clamp/glue/tap in splines.
http://www.pennstateind.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=PSI&Product_Code=SETIT&Category_Code=CLCOR
At this point I have two "nearly perfect" rectangular frames. (I measured the diagaonals and they were within 1/32!)

6. Next I make the corner posts. Hard to describe without a picture - see corner-tennon.jpg below. They are case height minus 3/4" long. This is to avoid interference with the rabbet bit (step 8).

7. Glue these in. Make sure they are flush with outside of frame on both sides. Here I use gorilla glue. Note too, they are glued on 3 surfaces. the bottom of the tennon and two sides of the tennon.

8. With the whole box assembled (like a box kite :-) rabbet out every face for the birch plywood. If your corner tennons are too long, the bearing is going to hit them and make non-rounded rabbet corners. The rabbet should be a 32nd or so deeper than the birch plywood - we'll flush it up later with a flush trim bit.

9. Cut your birch plywood to fit. The rounded corners are hard to get snug. The next one I make will be better.

10. Glue in all the panels.

11. Flush trim frame to panels (all six sides)

12. Roundover all corners

13. On the table saw (or if you have a large throat bandsaw and little blade drift) cut open the box. The ends are the trickies because the box has to stand on the end - no wobble. Top of case will not be as deep as the bottom (60/40 ish).

14. install oak edging inside box and bracing for latches, handle and the hinge. (1/4 plywood does not hold screws well) see handle-brace.jpg below. I also create something similar for behind the latches and on the ends of the case - I use 1/2" stock (this will make more sense when I post the final pics.)

15. Finish.

16. Attach hardware (piano hinge surface mounted, two draw latches, handle (on my bigger case, I have a handle on the end as well) Nylon glides for the hinged side of the case

17. Foam inside (egg crate for this one, mine is more elaborate)

18. Load up the equipment.

19. go shoot some paper :-)

Yes I'll post pics of the completed case. With any luck, Saturday.

Mark


Measure it with a micrometer, mark it with chalk, cut it with an ax.

Measure it with a Micrometer,
Mark it with Chalk,
Cut it with an Ax.

Visit my woodworking blog Dust Maker
PreviewAttachmentSize
corner-tennon.jpg
corner-tennon.jpg71.89 KB
handle-brace.jpg
handle-brace.jpg22.5 KB
MarkRD's picture

(post #107580, reply #6 of 24)

Also, I'm not sure what you mean by "banding"

Mark


Measure it with a micrometer, mark it with chalk, cut it with an ax.

Measure it with a Micrometer,
Mark it with Chalk,
Cut it with an Ax.

Visit my woodworking blog Dust Maker
Ardito's picture

(post #107580, reply #8 of 24)

What I meant by "banding" was your Oak frame. It looks real nice!

Dark Magneto

MarkRD's picture

(post #107580, reply #9 of 24)

doh!

I was moving cans of finish around (put up some new shelves in the shop).

Looked carfully at my can of linseed oil - it's not boiled! I can't believe it. The previous can I used was - must have 'brain farted' last time I bought the stuff.

The good news is that plain old linseed oil will 'dry' in 2-3 times the time of boiled linseed oil. I was able to speed up the process a bit by putting the project near a heater. The tackyness was completely gone last night, I sanded out the dust, brush strokes, and drips then wiped everthing down with clean rag w/laquer thinner. I let it sit overnight (just in case).

Put the final coat of urethane on this AM.

I'll assemble tomorrow and post images.

Mark

Measure it with a micrometer, mark it with chalk, cut it with an ax.


Edited 3/26/2005 11:21 am ET by Mark

Measure it with a Micrometer,
Mark it with Chalk,
Cut it with an Ax.

Visit my woodworking blog Dust Maker
lwj2's picture

(post #107580, reply #10 of 24)

Looked carfully at my can of linseed oil - it's not boiled! I can't believe it. The previous can I used was - must have 'brain farted' last time I bought the stuff.
*************

Pick up a can of Japan drier. If you add 1 tbs. (½-ounce, 15 ml) of Japan drier to make 16 oz of final cut finish, it will aid drying to about that of BLO.

You may have to get it from a pro paint store, I haven't looked for it in either of the borgs. The local Pittsburgh Paint dealer here (Roanoke, VA) carries it. Others may also.

Regards,

Leon Jester

Leon Jester, Roanoke VA

MarkRD's picture

(post #107580, reply #11 of 24)

So I add the Japan Drier to the BLO and mineral spirits?

Hmm

(And I love your term for HomeCheepo and Lowers = Borg. Perfect. (of course that term also applies to Microsoft and Walmart)


Measure it with a micrometer, mark it with chalk, cut it with an ax.

Measure it with a Micrometer,
Mark it with Chalk,
Cut it with an Ax.

Visit my woodworking blog Dust Maker
lwj2's picture

(post #107580, reply #12 of 24)

So I add the Japan Drier to the BLO and mineral spirits?

(And I love your term for HomeCheepo and Lowers = Borg. Perfect. (of course that term also applies to Microsoft and Walmart)
****************

Correct, add the Japan drier to the linseed and mineral spirits mix.

FWIW, I use a mix of linseed, tung and turps as a finish.

1-oz raw linseed oil
4 oz raw (or 100%) tung oil
15 ml (1-tbs) Japan drier
Gum turpentine to make 16 oz.

Can't claim originality on the borg. Picked it up from somebody here in Knots or over in Breaktime. Specifically, the Red Borg (or Orange Borg) and the Blue Borg.

(I lean toward the Orange Borg myself, Red Borg sounds like it is run by the USSR, and the KGB was MUCH better at running things than our local Orange borg is.)

Regards,

Leon Jester

Leon Jester, Roanoke VA

HowardAcheson's picture

(post #107580, reply #13 of 24)

>>So I add the Japan Drier to the BLO and mineral spirits?


No, you add the japan drier to RAW linseed oil., not BLO.


Howie.........
Howie.........
lwj2's picture

(post #107580, reply #14 of 24)

>>So I add the Japan Drier to the BLO and mineral spirits?

No, you add the japan drier to RAW linseed oil., not BLO.
************

Whoops. Thanks, Howie. That's what I get for posting when I'm dead tired.

Sorry 'bout that, folks.

Leon Jester

Leon Jester, Roanoke VA

MarkRD's picture

(post #107580, reply #15 of 24)

I actually knew what you meant so didn't bother correcting you, but I'm glad the correction was made anyway.

Mark


Measure it with a micrometer, mark it with chalk, cut it with an ax.

Measure it with a Micrometer,
Mark it with Chalk,
Cut it with an Ax.

Visit my woodworking blog Dust Maker
Gretchen's picture

(post #107580, reply #16 of 24)

Why not just buy some BLO and not add yet another layer of fiddling around to make the finish   finish.

Gretchen

Gretchen

lwj2's picture

(post #107580, reply #17 of 24)

Why not just buy some BLO and not add yet another layer of fiddling around to make the finish.
************

My original suggestion of adding Japan drier was to make raw linseed oil useable, the poster had purchased it by mistake.

As to why I don't use BLO, I prefer to use tung oil, I use raw linseed in the mix because I also use the same mix to make stains, linseed is better for suspending pigment than tung. (Or so I've been told.) Easier to have one standard mix.

One of these days I'll get some of the Tried & True brand of finish, which is a true BLO rather than a chemical version. Making it myself is (1) cost prohibitive and (2) SWMBO has flatly stated that I'm not heating anything with that low a flash point anywhere near where we live.

Leon Jester

Leon Jester, Roanoke VA

Gretchen's picture

(post #107580, reply #18 of 24)

I did realize that.  If he has to buy "something" to make something else, just buy the BLO and be done.

Gretchen

Gretchen

MarkRD's picture

(post #107580, reply #19 of 24)

If I use the raw linseed oil again, it will be on a project I can let sit for a very long time - it's a small can (quart?). Next time I'm out I'll pick up the boiled kind.

Now about tung oil - I've used "danish tung oil" and was quite pleased with the results. (Jewelery box for my wife)

Any particular brands you are fond of? I'm assuming I can top coat the tung oil with urethane for the high friction applications.

Thanks,
Mark

Measure it with a micrometer, mark it with chalk, cut it with an ax.


Edited 3/28/2005 8:13 am ET by Mark

Measure it with a Micrometer,
Mark it with Chalk,
Cut it with an Ax.

Visit my woodworking blog Dust Maker
HowardAcheson's picture

(post #107580, reply #20 of 24)

If you want pure tung oil, you must look for the words "pure" or "100%" on the label.  Most products you see are "Tung Oil Finishes" that contain little or no real tung oil.


True tung oil comes from the nuts of a tree in China. A product that is a true tung oil will have a label that says either "pure" or "100%". If it doesn't say that on the label, IT ISN'T TRUE TUNG OIL . Forget about all the other baloney and look for one of those two words if you want to use a true tung oil. If the label contains any other chemicals, except a thinner, you are not getting a true tung oil.  True tung oil takes about 3-4 months to fully cure and will emit an odor for that time.


"Tung Oil Finish" is a marketing name for products that the manufacturer thinks will result in a finish like the finish you get from a true tung oil. These "Tung Oil Finishes" may contain some true tung oil, but most do not. Their only claim to the use of the word "tung" is that it claims to give you the appearence of finish that results from true tung oil. When you buy a "tung oil finish", you are getting a "faux tung oil finish".


There are two types of "tung oil finishes". One is mixture of varnish, boiled linseed oil and mineral spirits (called an oil/varnish). The exact mixtures are proprietary but 1/3, 1/3, and 1/3 will get you real close. Some manufacturers add a dollop of drier to speed up the drying. This same mixture is frequently also called "Danish Oil" because it gives a finish that resembles the finish used on much of the "danish style" teak furniture imported in the 50's and 60's. It closely mimics a true oil finish but the addition of the varnish resins gives it more durability and protection.


Here are some oil/varnish mixtures:(*)
Watco Danish Oil
Deft Danish Oil
Behlen Danish Oil
Maloof Finish
Behr Scandinavian Tung Oil Finish
Minwax Tung Oil Finish
Minwax Antique Oil Finish
Velvit Oil


The second "tung oil finish" is one made from varnish and mineral spirits. The approximate ratio is 1:1. This is really just a thinned varnish just like the stuff sold as "wiping varnish". When one two or three coats are applied, it also mimics the finish produced by a true oil but it is harder than the oil/varnish above because it does not have as much oil. It is slightly more protective than the oil/varnish type or tung oil finish. For all intents and purposes it is a varnish finish.


Here are some thinned varnishes:(*)
Formby's Tung Oil Finish
Zar Wipe-on Tung Oil
Val-Oil
Hope's Tung Oil Varnish
Gillespie Tung Oil
Waterlox
General Finishes' Sealacell
General Finishes' Arm R Seal
Jasco Tung Oil


One way to tell whether the product is an oil/varnish or a wiping varnish is to read the application instuctions. Oil/varnishes are applied, then given some time to set, then wiped dry. Wiping varnish products are wiped on an left to dry (no wiping off).


Finally, I'm not saying that any of these products are not good. They are what they are and can give you a good finish when properly applied.


(*) Thanks to Bob Flexner "Understanding Wood Finishes"


 


Howie.........
Howie.........
MarkRD's picture

(post #107580, reply #21 of 24)

Thanks, Great summary.

I used Watcos on my wife's jewlery box, and it looks pretty much the same (a bit glossier) as the Linseed oil and mineral spirits. Now I know why. It's basically the same stuff with a bit of varnish thrown in. I'll make my own in the future.

Have you use true tung oil? Is it worth the "months" of off-gassing?
What other things should I know about Tung. When can I cover it, what can I cover it with. How much does it darken????

Thanks,
Mark


Measure it with a micrometer, mark it with chalk, cut it with an ax.

Measure it with a Micrometer,
Mark it with Chalk,
Cut it with an Ax.

Visit my woodworking blog Dust Maker
lwj2's picture

(post #107580, reply #22 of 24)

Mark, I've used the 100% Tung oil sold by WoodCraft and also ordered it through the local Pittsbugh Paint dealer.

Both have worked well, I've stuck with the local folks because I can get it without shipping charges (it rides on all their order for the week, hence no shipping charges). Plus, I like supporting local businesses. The cost per litre is about the same.

Regards,

Leon Jester

Leon Jester, Roanoke VA

MarkRD's picture

(post #107580, reply #23 of 24)

Hi DM,
You can check out the bow case now in the gallery at:

http://forums.taunton.com/n/mb/message.asp?webtag=tp-knots&msg=22830.1

The rest of the pics are at http://www.pbase.com/durrenm


Measure it with a micrometer, mark it with chalk, cut it with an ax.

Measure it with a Micrometer,
Mark it with Chalk,
Cut it with an Ax.

Visit my woodworking blog Dust Maker
HowardAcheson's picture

(post #107580, reply #7 of 24)

Whether you use mineral spirits or naphtha, the BLO takes the same time to cure.  The thinner has no affect on the properties of BLO except to make it thinner.  Once the thinner evaporates you are still left with BLO.


BLO should be ready to be overcoated with an oil based finish within 4-5 days.  Overcoat it too soon, an the clear finish will be slow to dry.


Howie.........
Howie.........
Steves_Gift_Shoppe's picture

Urethane over Linseed Oil (post #107580, reply #24 of 24)

The best results I have had for urethane is to let it set in the open air on a warm sunny day.  For my situation, I have an enclosed, screened-in deck and that does well to keep the bugs away and not get into the work.  I know that urethane sets well with an infared lamp.  Sunlight on a warm day in the 80s is perfect and very fast curing times.  If your work is curing in a cool place, it's going to take longer to cure. Hope this helps.