Furniture Finishes - Varnish verses Polyurethane

Discussion in 'All Things Boats & Boating' started by kach22i, Feb 16, 2011.

  1. kach22i
    Joined: Feb 2005
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    kach22i Architect

    Application: Interior use, new wood, Baltic Birch Plywood with exposed edges.

    Availability: First off I don't even know if I can get real varnish any more (Carver-Tripp is gone). All the stuff on the shelves looks like the exterior marine grade with UV protectant added. Special order for interior grade stuff, wait a week or do a couple hours of driving and burn some gas.

    Why I like Varnish: gives wood a honey glow, some call it amber.

    Why I don't like Varnish: the honey glow goes away after a few years, and the wood looks lighter, bleached out. Some call say it clouds. Also it may have a longer drying time.


    Why I like Polyurethane: I can get MinWax clear satin anywhere, anytime. It is supposed to be more stable color wise than Varnish and more durable.

    Why I don't like Polyurethane: it gives wood a reddish hue (oil based stuff does this) and looks flat, dry or dead when compared to varnish (even the glossy does not have the same depth of sheen). It's plastic, right? Now your wood looks plastic or fake, and it feels different than varnish. Varnish has a natural smoothness, Polyurethane is more rubbery, not as hard shell like (guess it may not scratch or chip as easily?).


    I'm looking to hear from die hard fans of varnish.

    I'm looking to hear from the converts who now swear by oil based polyurethane.

    I'm looking to hear from those who have gone green and trust the water-born alternatives.

    Old varnish/plywood project:

    How different is Marine Varnish than an old fashion Interior Grade furniture varnish?
  2. gonzo
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    gonzo Senior Member

    Polyurethane is a varnish. There are many kinds. The base can be tung oil, linseed oil, modified alkyd, polyurethane, urethane, etc.
  3. CDK
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    CDK retired engineer

    The hue caused by polyurethane on wood I cannot deny.
    It doesn't bother me because I don't like wood for other reasons: it shrinks, cannot be welded and is food for a number of insects and rodents. You shouldn't use food as a construction material.

    But a lot of people love wood, so there is a solution to get the durability of polyurethane without the hue.
    I have here standing near my feet a carton of "Chromoden", lacquer for new wooden floors (parquet). It contains 3 jars, 2 are the components for an extremely durable polyurethane coating, available in eggshell or glossy.
    The 3rd is a low viscosity colorless lacquer to impregnate the wood before the polyurethane is applied. The natural color of varnished wood is combined with the durability of polyurethane.

    In this country ingredients need not be listed on the can, but there are the international pictograms for inflammable and health hazard on can #3. I smell toluene, xylol or cellulose thinner, they are all alike to me, it probably is plain cellulose lacquer, highly overpriced for this special application.
  4. michael pierzga
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    michael pierzga Senior Member

    For yacht interior work, I like to do the build up coats with polyurethane, wet on wet. Once the buildup is the correct film thicknes, sand flat with fine paper and finish coat with Polyurethane Paste varnish , applied with a cloth pad. . easy to use and leaves a dust free matte finish. No particular brand...several on the market locally and they all seem to work fine.
  5. gonzo
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    gonzo Senior Member

    There are also laquers, oils and rubbed finishes. I think kach22i needs to narrow the field more.
  6. Tiny Turnip
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    Tiny Turnip Senior Member

    I've used OSMO Polyx Oil (aka OS Hardwax Oil) extensively, on kitchen worksurfaces, bare oak stairs, and I like it very much, but its not cheap.
    Application is very easy - can be ragged on, and it soaks in, rather than building up a coating. It doesn't give a high gloss finish, it is robust, and easy to reapply in a high wear area, without having to do the whole thing again.
  7. gonzo
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    gonzo Senior Member

    Some of the water base clears work fine too. House flooring, which gets a real beating, lasts several years.
  8. rasorinc
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    rasorinc Senior Member

    I've built a lot of fine furnature out of Iron Bark (eucalyptus) and finished with teak oil and added a tint shook it up in a jar and hand rubbed it in with soft rags. It was a work of love and after 5 coats it had a beautiful deep sheen the color I wanted. Got wonderful comments lasted a few years and I just rubbed another coat on and it looked new again. I've done this with several wood and colors and no problem.
  9. kach22i
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    kach22i Architect

    Thanks for the input, and I like the amber over reddish hue just to be clear. The flooring finish in three parts starting with a lacquer is something I have read only a couple of times before and seems promising.

    I talked to "the wood guy" at the local hardware store (Stadium) who claims to spend most of his time at his real job ankle deep in wood shavings.


    Per his suggestion I'm going to try a couple coats of sealer (alcohol based) and a top coat of oil based polyurethane. Theory has it that the sealer will give it that amber hue I like, but the sealer is sensitive to cleaners and chemicals and should be protected. That is were a top coat of polyurethane comes in.

    He also warned me away from steel wool because over time residue may oxidize and discolor the wood. Suggested fine sandpapering between coats if I must (like a car finish).

    One important factor I forgot is that 11 years ago when I built my own office furniture out of Baltic Birch plywood I did the varnishing at midnight in the office, and cracked open the windows. This project is being built in my basement, with a wife and cat in the home. The sealer smells a little like a good but sweet bourbon, and the polyurethane is mild compared to the fumes varnish puts out.

    I've read at least one vote against Minwax as a brand, the shelves are full of other brands. Name a few you like better.

    I'll post the test pieces in a few days.

    This wood finishing is for my no-box loudspeaker experiment/prototype.
  10. gonzo
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    gonzo Senior Member

    I have found minwax to be of good quality. My kitchen counter and cabinets and sometimes boats have it.
  11. kach22i
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    kach22i Architect

    The small can I bought seems really thin compared to what I remembered polyurethane to be like.

    Is thin better than thick so that it penetrates?
  12. gonzo
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    gonzo Senior Member

    I am not sure of the difference in penetration. However, it dries really fast so you can build up several coats pretty fast.
  13. cthippo
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    cthippo Senior Member

    I use the Minwax Helmsman spar urethane for most of my visible wood. dries reasonably quickly, even in the cold, damp weather here and builds up to a nice shine. It can darken the wood up quite a bit depending on what you're putting it on.

    While we're on this topic, can someone recommend a totally clear brand of polyurethane? I'm going to be coating the skin on my kayak soon and I don't want the finish to change the color of the underlying fabric.
  14. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Traditional varnishes and polyurethanes are both alkyd (oil) based. The polyurethanes fall into two general categories, activated (two part) and single part. There are also some water based versions around, but I wouldn't trust these in a marine environment just yet.

    The LPU's such as Bristol Finish are very hard, tough and durable. For the most part they have the same color as traditional varnish (wasn't always the case), though less build up with subsequent coats, unlike varnish.

    The varnishes are still available but now have all sorts of junk in them. These modifiers don't really help all that much, but do improve it's market value.

    The bottom line is you need to compare apples to apples. Varnish is a term now used for just about any clear coating. Comparing a highly modified alkyd base like the MinWax Spar Varnish (which truly sucks compared to real varnish) to a fast drying polyurethane just isn't comparing apples to apples.

    If you want real varnish, then you have to accept it will take all damn day to dry, but it's an honest coating, easy to repair, over coat, blend, etc. On the other hand if you want to apply 5 coats of clear in a single day, then one of the modified polyurethanes is the ticket, but it'll be difficult to repair, more difficult to apply, may have color issues and cost more too.

    In the end it's what you want, and each choice, from WR-LPU's from System Three to pure alkyds from Decks 'Olje, you should do your research on similar products, as their physical attrubutes will not match up other wise.

    As far as shellac, well this isn't a weather deck coating. It's alcohol solvent as well as easily affected by other chemicals, more importantly UV. This isn't a material that should ever be consider a finish coating. There are much better ways to lock down the grain then shellac.

    The LPU's can be had completely clear.

  15. CaptBill
    Joined: Jan 2010
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    CaptBill CaptBill

    If you are set on the 'old school spar varnish' these guys sell it. EPA only allows quarts to be sold. Lots of info.....

    If you want the amber tone simply use the new technology varnishes and tint it a tiny,tiny bit. Check around for the best way/color etc. to go with tinting.
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