My wife collects orchids and we are getting ready to build some more birch cabinets to display them. I need a clear coat for the interior that can withstand humidity and some direct contact with water droplets.
In the past we have used Minwax oil-based polyurethane or Envirotex-Lite, a solvent free epoxy. We’re looking for something different.
Oil-based poly is just a bit less water resistant than we’d like. It’s also a lot of time to put on enough coats and have them offgas to the point that it is safe for the orchids. What we really don’t like about it is having to repair or recoat it after a few years. In fact OB polyurethane’s water resistance would be fine if it were easier and quicker to repair or recoat.
The Epoxy is nice but a bit fussy and very expensive.
So we’re looking for something that…
1) is equally or more water resistant than oil-based polyurethane.
2) is a sprayable finish.
3) can be built up and act as its own sealer.
4) allows easy repairs with minimal turn around time.
We don’t mind a slightly plastic look or paying close to epoxy prices.
So I’m wondering how a catalyzed lacquers/conversion varnishes stand up to our criteria?
I appreciate any input.
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A general rule for finishes Chris - the more durable it is, the harder it is to repair.
Here's a link to a chart that shows the relative durability properties of spray finishes - http://www.furniturefinishwizard.com/awi/awichart.htm . If you want to get maximum water-resistance from a spray finish, a catalyzed polyurethane is your best choice. One of your local automotive paint suppliers can get you set up with the product and data sheet.
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Thanks.So does something like Minwax interior polyurethane fall under the polyester/polyurethane column? I'm guessing not since its listed as having the same water resistance as catalyzed poly.I did a bit more shopping around today and the only catalyzed lacquer available locally in small quantities is Magnalac.How can I expect Magnalac to compare to Minwax?If Magnalac has slightly better or similar water resistance I'll switch to it for the quicker dry times and easier recoating down the road.If not, I'll continue dealing with oil-based poly.
Go to http://www.homesteadfinishing.com, and look at their cataloug. Many CAT/CAB Target coatings available, and Jeff Jewitt knows his stuff.
Magnalac has received a lot of bad feedback on the Professional Finisher's forum at WoodWeb Chris. The Magnamax has a much better reputation. Both are a pre-catalyzed lacquer and fall unde the TR-2 heading on the AWI spray finishes chart. You'll get better water-resistance from an oil-base poly with enough coats.Oil-base varnish/polyurethane isn't listed on the chart because it's not considered a spray finish due to the slow dry time.Epoxy does have the highest water-proofing ability and is really your best choice. One of the water-base spray varnishes from http://www.targetcoatings.com may be an option; I like their finishes but haven't used them in such a wet environment so I'm not sure where they stack up in comparison. You can post a question on their forum or give them a call.Paul S
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try compliant spray systems. They sell a crosslinker to add to their Enduro poly that hardens the finish & increases water resistance.
Have you tried spar varnish? I finished my dog's food/water table with three coats of Minwax Helmsman's Spar varnish two years ago. It has effectively been under water since then, with no visible wear.
-Matt
It has effectively been under water since then, with no visible wear
What about the floor next to it?? MY DOGS make a mess with water!
Chris, I use Sherwin-Williams catalyzed conversion varnish. I have been finishing for about 25 years and this is the best product I have used. Easy to use, 24 hours after shooting its is inert, easy to repair and has three available sheens-dull, medium rubbed and bright rubbed. I make kitchen cabinets and high-end millwork and will use nothing else any more. I have to say it prefers to be sealed with its companion product catalyzed vinyl sealer which is much easier to sand than the CV. In the medium rubbed it looks like an oiled finish which I like. Hope this helps. Aloha, Mike
I'm with Mike. I love Sherwin Williams Kem-Var conversion varnish in the medium hand rubbed. When I left a big custom kitchen shop to go on my own I will freely admit that finishing was my weakest area. I tried lots of diferent finishes trying to find something that worked for me. I saw a small article in FWW about this product and how it is perfect for the small to mid sized shop and about the quality. I figured I would give it a try, and haven't looked back since. I agree that even though it is made to be a self sealer I prefer the vinyl sealer that Mike sugested.
I have not only used it in cabinetry and furniture work but also for a builder I do other work for on all his trim and doors because he has never been able to find anyone to give him that quality finish. I also have a boat that I fish trout and salmon with on Lake Michigan, and have used it on the dash board and trim around the cockpit as well as the board that I has all my rod holders and downriggers on. It still looks like new, other than some dings from real abuse, after 6-7 years. It sees the Lake about 3-5 days a week and has seen more than it's share of wet, dry, cold and hot with out checking or crazing. When I started with it I thought that would be a great place to test it's durability and It's performed better than I had hoped for. Your application should be no problem.
The one problem you may have is that it is only available in 5 gallon cans with about a year of shelf life. If you are going to use it for other projects that should be no problem. It is going to be cheaper than a good epoxy and give you a "furniture quality" finish with alot less effort.
Good luck, and post pics when you're done!
Brian
Edited 5/12/2005 8:39 am ET by BrianF
Have you thought about water-based polyurethanes? They dry harder and faster than oil-based, and also dry clear. The wear factor is such that they are often used to finish hardwood floors. They can also be thinned up to 10% with water, and cleanup is much easier.
Regards,
Ron
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