question about story in FineWoodworking

[Mike S.]

I was reading the Feb. 04 issue of Fine Woodworking and the article about finishing. He mentioned using varnish. Is this the same as poly or is he writing about something else? Thanks

[Mike in Mystic]

there are many things that are "varnish". Polyurethane is AN example of varnish. Varnish, in general, is simply a mixture of oil and resin. In that article he talks about using a "short oil varnish" (IIRC). This type of mixture is (obviously) a greater percentage of resin vs. oil, so it cures harder. The type of oil and type of resin are important, and that's why there are so many types of varnish out there. In that article, he used a varnish with an alkyd resin. This differs from others using phenolic resin. Polyurethane varnish is made with (you guessed it) polyurethane resin (and usually, i think, is mixed in some part with alkyd resin).

Various properties vary, such as bonding propeties, cured appearance (hence the boloney out there about polyurethane looking like plastic - it's possible, but not a definitive property), yellowing character, etc.

In short, the varnish in that article was a short-oil alkyd varnish, so, no, it wasn't polyurethane.

[Myxylplyk]

Well said Mike, as usual.

Myx

[Mike S.]

Mike, thanks for the info. Now is this short oil or alkyd varnish come under a brand name or what do I look for, I checked a few places I shop online and they weren't to specific to the type.

[Mike in Mystic]

That's a good question, and one I'm afraid I don't know. I haven't ever used an alkyd varnish myself. That article had a can of one showing, did you search on that name (I don't have the article in front me, so I don't remember what it was). I'm sure someone here can tell you.

By the way, I found this article which might prove helpful to you as well:

[Mike in Mystic]

I found this one:

at the "Old Masters Super Varnish" towards the bottom of the page.

Honestly, as long as you don't get a spar varnish, and let the varnish cure sufficiently (I'd say at least a week if not two), then you should be ok for indoor use. The resin type is probably less important. If you want a really hard surface, try a rockhard tabletop finish - most of which I've seen are polyurethane varnishes. As always, you need to experiment with the specific products you have in your hands and see how the finish looks to you on the items you're working on.

Mike

[Mike S.]

Thanks for the info Mike, finishing is where I'm still experimenting and learning. I've been woodworking for about 3 yrs. and finally getting the shop set up with decent tools. I've used poly, wipe on poly, shellac and several others including Waterlox finish. I started out using cheap pine, then the pondorosa pine which is a little better and now that I have a planer and jointer I'm getting into the hardwoods. Projects I'm working on now are red oak. Again thanks and have a great weekend.

[Tim Mueller]

Most varnishes in the home centers / paint stores today are alkyld, or, as pointed out above, an alkyld - poly blend. Very few have any phenolic resins in them, and those tend to be marine. For a few years now, the CAS numbers of the produc's components have been listed on the labels, and they will call out the different resins, sometimes more than one of the same type (for instance, two different CAS numbers for alkyld resins). The natural resins tend to remain slightly soft - as a matter of fact, the Epifanes guys (best marine varnish in the world, IMHO) like to say that a natural resin film isn't completely cured until it's peeling off. Polys on the other hand do get hard, which makes them attractive for high-abuse areas: floors and table tops.

Varnishing red oak can be a real pain, because of the very open pores. I recently went through the exercise with a couple truck loads of 8/4 edge glued red oak table tops for a restaurant/bar. Without some sort of filler/sealer, the pores just will not build a film and give you a smooth surface. (Six coats later, they were still absorbing finish.) Also, without a sealer, pinholing of the finish over the pores can be an issue. (As I understand this issue, the pores suck in finsih and the evaporating solvent creates a bubble and then a pinhole as it escapes).

[Mike S.]

Can you use a sanding sealer to solve the problem or is there some type of special sealer. Also will it work over stain?

[Larry Jaques]

On Sat, 3 Jan 2004 09:36:27 -0500, "Tim Mueller" brought forth from the stain-smeared, saran-wrapped depths:

Why does everyone and their copulatin' brother want a SMOOTH finish on a nicely textured wood? Why don't you all just use a smooth, closed-pore wood if you want a copulatin' mirror?

There. I feel better. (Sorry, Tim.)

======================================================== TANSTAAFL: There ain't no such thing as a free lunch.

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[Tim Mueller]

Well, sometimes you want to know that the wood's pores are not sucking in oil from spilled french fries, or milk shakes, or coffee, etc. What's the real risk? Low, probably, but you're not the one who has to convince the Health Department inspectors when they come to renew the yearly license.

[Tim Mueller]

Yes, we stained the tops with a witches' brew, then sealed and varnished. The sanding sealer was made by the varnish manufaturer. After some hours on the phone with our varnish manufactuer's tech guys, this is what I can conclude:

-- Compatibility is guaranteed only by testing.

-- With the advent of the low VOC regulations and the consequent product reformulations, manufacturers test for compatibility only within a narrow spectrum of products, typically their own. So, if you're doing what we did, which was stain with Minwax and varnish with McCloskey, caveat emptor. (We now use SolarLux stains and dyes, no longer Minwax. That job was an interior renovation, so we had to match the existing colors and didn't have time to develop new formulas with different products.)

-- Talk to the manufacturer's tech support. They are (usually) happy to help you head off problems rather than deal with them afterwards.

-- Compatibility is guaranteed only by testing.

[B a r r y B u r k e J r .]

I took a finishing class taught by a guy with 20 something years as a finishing products sales engineer. Part of his job during that time was to help his customers, which were cabinet and furniture shops, rather than retail customers, figure out what went wrong.

He emphasized "systemizing" with finishing products. In other words, use one manufacturer's products from start to finish, whenever possible. He never talked WHICH manufacturer, he encouraged us to make our own decisions.

If a systemizing wasn't possible, just as Tim mentions above, thoroughly test it first! Another point the instructor mentioned was that the best tests have some time after them, before declaring the test a success. He mentioned seeing combos that seemed OK for a day or two, only to fail a week or two, or even longer down the road, as one of the components finished curing.

Barry