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poly vs. lacquer

BrianDerr's picture

poly vs. lacquer (post #111599)

Is poly just as good of a finish for higher end kitchen cabinets as sprayed lacquer? I think that durability is the deciding factor in this case. I'm considering a gel poly applied with a cloth, so brush strokes, drips and dust shouldn't be issues. Appearance should also be a consideration, of course. The material is unstained cherry. I understand that poly is thicker, but when applied with a cloth it should be much thinner than with a brush. It would take some time to do this by hand, but I think the price and convenience of it would outweigh. I don't think I'd be comfortable spraying in my small attached shop, nor do I have any equipement. I'd also like to avoid carting my precious work around town. I guess hand applied lacquer would also be an option, if it would dry quickly. Any opinions at all?

Brian

MikeHennessy's picture

(post #111599, reply #1 of 12)

I used water base poly on my kitchen cabs. They're about 5 or 6 yrs old now, and no sign of wear. I did spray them with HVLP, tho' that should'nt make much difference in the durability.


Mike Hennessy
Pittsburgh, PA

Mike Hennessy
Pittsburgh, PA
Everything fits, until you put glue on it.

SteveSchoene's picture

(post #111599, reply #2 of 12)

I would consider a traditional resin varnish thinned to be a wiping varnish.  One ready mixed one is Waterlox, which comes in several gloss levels.  For kitchen cabinets probably the Satin would be the best choice.  I'd start with about half a dozen coats of the original/sealer  which is a semi-gloss varnish, and then switch to Satin (probably thinning it a bit since it comes a little thicker than the Original/Sealer) for a final coat or two. You can also thin any good varnish, such as McCloskey Heirloom or Pratt & Lambert 38


These varnishes would be dramatically more durable and protective than sprayed lacquer--which isn't used on commercial cabinets these days.  Commercial cabinets use catalzed finishes, often conversion varnishes. 


Polyurethane varnish has a bit more resistance to heavy abrasion, which makes it well suited for floors, but, in general, the advantages of the readily available single part polyurethane varnishes don't really apply to furniture or cabinetry.  

Test your finish on scrap, FIRST, or risk having to scrap your finish.

oldusty's picture

(post #111599, reply #3 of 12)

  Hi Steve ,


              You said sprayed lacquers are not used on commercial cabinets these days , but mostly catalyzed finishes . I would agree and disagree , catalyzed lacquers are quite common on high end and commercial custom cabinetry and used extensively industry wide .


   For a  bar top , or floor or countertop lacquers are not the toughest choice by far .


                dusty

BrianDerr's picture

(post #111599, reply #4 of 12)

correct me if I'm wrong, but poly is a 'resin varnish'. Does 'traditional' mean an oil/varnish mix? Oftentimes, when talking finishes we get sidetracked to talking in brand-names, which kind of bypasses the fundemental discussion . . . so you are saying that poly is more durable than lacquer, but why not for cabs/furniture? The thickness of the finish? I just want to know specifically what your criticism of the gel poly is, because I really am interested in you opinion.

Brian

SteveSchoene's picture

(post #111599, reply #5 of 12)

Traditional varnishes are made with alkyd or phenolic resins and are varnishes not oil/varnish mixes.  They cure to a hard film, typically harder than the polyurethane varnishes you find at the local paint store or big box, but look basically the same.   Polyurethane is just a different plastic or resin used in making the varnish but all are varnishes alike.  In single-part polyurethane varnishes it is usually combined with alkyd resin.  Polyurethane resin varnish is tough and resists heavy abrasion a bit better than the traditional resin varnishes.  But that abrasion resistance comes with a price.  Polyurethane varnishes can be a little less clear, have more issues with adhesion, and most importantly to me, are more difficult to rub out to an even sheen.  The extra abrasion resistance is great for floors but hardly needed for furniture that isn't walked on.  Why accept the issues that come with poly when its strength isn't really needed? 


Gel poly is just a polyurethane varnish with a thixatropic agent that lets it remain a gel until disturbed in the application process.  My experience with the gel poly hasn't been very satisfactory and it hasn't been as durable as I would have expected.  That's likely because you don't realize that such a thin coat is going on and, like a wiping varnish, it would really take 6-9 coats to have real varnish protection. 


All of these varnishes alkyd, phenolic, and polyurethane, are more durable than basic nitrocellulose lacquer.  The NC lacquer is an evaporative finish and remains solvable in the same solvents that dissolve it in the beginning.  It is also more vulnerable to heat and moisture damage.  (White rings are mostly an issue with lacquer.)  Other solvent based products--catalyzed lacquers (pre- and post-) and conversion varnishes do offer increasing chemical and abrasion resistance.  Few commercial cabinet makers use the basic NC lacquer any more, with conversion varnish becoming more and more common, though post-catalzyed lacquers are also used. 


Edited 2/1/2008 4:25 am ET by SteveSchoene

Test your finish on scrap, FIRST, or risk having to scrap your finish.

BrianDerr's picture

(post #111599, reply #6 of 12)

Perhaps you could educate me on the differences between NC, conversion and post-catylized? I'm interested. Would one of these rival poly in durability? And since it sounds like poly is the most durable to begin with, for kit cabs I think I could get away with fewer than the 6-9 coats recommended. I'm not interested in rubbing out for this project, but the issue of adhesion gets my attention. Thanks for the free advise, Steve.

Brian

SteveSchoene's picture

(post #111599, reply #7 of 12)

NC lacquer is the long time furniture standard. It is an evaporative finish, dries quickly and quite hard, allowing it to be rubbed out very well.  But, it always remains solvable in its original solvents.  That tends to make it susceptible to damage from household chemicals.  To address these problems cross-linked finishes were developed that could still be applied in the same way as lacquer.  Post catalyzed is one of these.  The cross linking makes it tougher and more durable.  Conversion varnish is also a two part finish and generally even more durable, but also generally very hard to repair if it were damaged or not sprayed with good off the gun perfection.  The post catalyzed and conversion varnish have some serious solvents and toxic (until cured) cross linking additives.  They also remain explosive while being applied.  Consequently, having proper facilities to spray these safely is important and largely relegates them to commercial shops. 


Single part polyurethane varnishes do have more abrasion resistance than alkyd and phenolic varnishes, but otherwise have quite similar durability characteristics.  All of these are more abrasion resistant than NC lacquer.  There is no real advantage to polyurethane varnish over the others for kitchen cabinets. 


As to the number of coats, the 6-9 recommendation comes from the fact that it takes at least 3 coats of wiped on finish to generate the equivalent to 1 full strength brushed on coat.  Thus, this is equivalent to only about 2 or 3 thin brushed on coats.  Going to poly from alkyd or phenolic won't reduce the number of coats needed for good coverage.   

Test your finish on scrap, FIRST, or risk having to scrap your finish.

BrianDerr's picture

(post #111599, reply #10 of 12)

Thanks, Steve. Maybe I'll practice with some of the traditional varnishes you recommend.

Brian

Herebrooks's picture

(post #111599, reply #8 of 12)

Hi Brian: I had a small shop for many years and ran into some of the problems with finishing you described. After many experiments(and many failures) I arrived at finish that worked for me. I would apply a thinned down polyurathane sanding sealer(add a couple of capfulls of japan drier to aid with dry time) with a pad painter and let it soak in for a few minutes before wiping off the excess(watch those rags though) Next day, sand lightly with 320 no fill paper to get a really smooth surface. Since dust is your enemy in final finishes, I used a quick dry polyurathane and had a bank of halogen lights suspended above my finishing table that I could raise or lower depending on what I was finishing. I did spray my final finish, but I have no doubt you could brush it on and get the same effect. I also had an exhaust fan to take the fumes away( not an aggressive one that would pull dust from the rest of the room, but gently.(wear a mask!) With the lights, I got the open time down to seven minutes. I wouldn't try this with lacquer though, it's quite a bit more volitile than poly.


 

9michael9's picture

(post #111599, reply #9 of 12)

POLY

Herebrooks's picture

(post #111599, reply #12 of 12)

Yeah! I used Benjamin Moore antique flat that gave a waxy look to the finish and wore quite well. I think the secret to the seven minute open time was the fact that I thinned the finish with naptha and used a viscosity cup to get just the right thickness to go thru my HVLP system. The evaporation rate was enhanced by the heat the lights were putting off. I was in a house fire once with flames coming thru the floor of my bedroom so, since then, I've been a little paranoid of fire. I was always extremely careful not to get the fumes(or spray cloud) near the lights. I would spray with the lights off, wait until the exhaust fan had done it's work, and turn the lights on to heat up the finish(Three 500 watt halogen lights mounted on a crossbar) I also put the lights on a dimmer so I had some control. Note: always have an extinguisher close by!!! I never had a problem though.


 Bill

BrianDerr's picture

(post #111599, reply #11 of 12)

Seven minutes. Wow! Thanks for the warning about lacquer.

Brian