For those of you who know Steve Mickley from either the Hardwood Lumber & More store or his side job of hosting Wood Magazine's finishing forum, you know his distaste for polyurethane.
While I have and do occasionally use it, I think it's probably one of the most overused products there is. Many people think it is just the universal finish (I often have customers tell me they have polyurethane on their factory furniture (which would be a first to me)). Just like people think Polyurethane glue (Gorilla Glue) is just the ne plus ultra glue.
I had a customer a few years ago that was a wood turner. He'd read FWW's article on wipe on finishes that concluded Minwax Wipe On Poly as the winner. So this guy stocked up a whole cabinet with the stuff.
* First, now really, do you need the protection of a polyurethane on something that sits behind glass on a shelf?
* Second, that test was programmed to have a winner. By taking widely varying products, ignoring both label directions and common knowledge for application, the outcome was determined before the test was started.
* There are easier to apply finishes that would look much better on his objets d'art
So... What finish should you use? I don't care -- as long as you choose it based on knowledge and not habit. I would not think the exact same finish would be the best for a dining table top, a formal chair, a jewelry box, a mantle, and a piece of art sitting on a shelf. None of these have the same usage requirements, so why would one finish be the best for all?
Below are some of my thoughts:
Polyurethane:
Pros Cons
inexpensive Yellows considerably
easy to find difficult to repair, difficult to buff to a different sheen
abrasion resistant learning curve on application involving sanding, thinning, and brush stroke
good water resistance Low UV resistance
Can look "plasticy" if applied too thickly
Prone to brush marks
Apply with brush or pad
Examples: Minwax, Minwax, Minwax, Minwax, Varathane, Cabot Poly, General Arm-R-Seal (wiping), Sherwin Williams Poly, store brand polys
Note that "abrasion resistant" does not mean hard. In fact it mean soft and rubbery.
Non Poly varnishes (alkyds and phenolic)
Pros Cons
Good appearance Harder to find
Non-yellowing More expensive
Hard, able to rub out
Good to excellent water resistance
Better UV resistance
Light to dark amber coloring (depending on choice)
Brush or pad
Examples
Alkyd: Sherwin Williams Fast-Dry (non poly), Pratt & Lambert #38, Cabot 8000 series (was McCloskey's Heirloom), Minwax Tung Oil Finish (yes, really)
Phenolic: Waterlox, Behlen's Rockhard
Shellac
Pros Cons
Excellent color and depth Less water resistance
Available in different shades Limited shelf life once mixed with alcohol (1-3 years)
(super blonde, blonde, lemon,
orange, garnet)
Dries very fast (20 min)
Hard, easy to rub
Extremely easy to repair / refresh
Spray, brush, or pad
Barrier coat for silicone contamination
or dissimilar finishes, knot bleed, smells, etc.
Examples: Zinsser has a virtual monopoly on US products
Lacquer
Pros Cons
Good color and depth Slightly less water resistance
Dries very fast Smellier during application
Hard, easy to rub
Extremely easy to repair / refresh
Spray or brush
Oil
Pros Cons
Easy to apply Virtually zero water resistance
Easy to renew Needs periodic renewal when dull
Flat, in the wood look Has to be done exactly right to not fail (Tung)
Adds good figure Darkens some woods (good or bad, depending on what you want)
Tung oil much more expensive with little difference to BLO.
Pad or brush and wipe off all excess
Examples: Boiled Linseed Oil (BLO), 100% Tung Oil
Oil-varnish blends
Pros: Cons
Easy to apply Less water resistance, but more than oil alone
Easy to renew Hard to determine what product to buy, unless you mix your own.
More in the wood finish with light film More expensive than buying components and " " " "
Advantages of oil and some Should not build up much of a film finish or it will be soft.
protection of varnish
Pad on, pad off excess before it becomes tacky
Examples: Danish Oil (various mfr.), Watco, ValOil, Minwax Tung Oil Finish (which is neither an oil, nor Tung Oil), Minwax Antique Oil
Recipe for make your own: start with 1/3 each : Mineral spirits, Varnish of choice, Boiled Linseed Oil
For a thinner mix, add more mineral spirits.
For a faster build, add more varnish
For a softer finish, add more oil.
Water borne (acrylics)
Pros Cons
Water white adding little to no color Can appear "blue" and looks too cool on woods we are
Harder, easier to rub accustomed to seeing amber (cherry, walnut)
Little odor Can be prone to foam or brush mark without technique
Very fast drying
Easier to repair
Good for very light woods, painted & pickled finishes
Spray or brush
Examples: Polycrylic (note that this is primarily acrylic with very little poly), General Finishes, Valspar, Varathane Water Based Poly (again acrylic)
There are a few other finishes out there that are not appropriate for home shop use without specialized equipment, personal protection and ventilation.
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