Wipe on: Poly-U, JAPAN, & Tung oil

[Cliff Rohrabacher]

I have played with thinning alkyd Poly-U with mineral spirits and xylene.

I found I liked Xylene better from a finish perspective because it seems to dry faster and clearer. But, I needed to use a carbon mask to use the stuff. Xylene is nasty stuff.

Now I am thinking about using JAPAN dryer. I've seen formulas that call for equal parts of Tung oil with the poly-U and some old school turpentine.
Ostensibly the turpentine makes it flow better.

I can't figure out why any one would want to add tung oil since it'll just slow drying down and make the finish a tad duller. My reason for wiping a finish on is to get it to dry fast so as to avoid the dust I have always around me.

I suppose one could compensate for the tung oil and boost the drying time by adding more Japan but that risks crackling in the poly-U as it drys.

Any one use Japan?
Do you also use Tung oil?

[Jim Becker]

The Tung Oil in the home-brew formula is to create a varnish oil..."Danish Oil", if you will...that mostly soaks into the wood and doesn't really generate a film finish. The turps are generally used to thin it to wiping consistency. (Today, we would be more likely to use mineral spirits and BLO to accomplish the same thing and get a faster cure)

No idea on the Japan drier...my impression of that stuff is "a little dab 'l do ya..."

[Steve Schoene]

VM&P Naphtha has a faster evaporation rate than xylene. (So does Toluene, but you want to breath that even less.) Using thinner to make a wiping varnish has some effect on the cure rate, but not really as a result of the speed of solvent evaporation, just because the thinner coat of varnish has more oxygen exposure to speed the cure. The solvent evaporation speed has more to do with how quickly the surface gets tacky, but not quite so much as how fast it sets out of dust.

As far as adding Japan drier goes I don't really recommend it. The varnish manufacturers pay chemists (or actually the chemical companies that actually make the stuff do) to formulate the driers for a particular varnish. Why mess with that by adding driers that may, or may not, be compatible with the manufacturers driers.

Once you start adding oil, with or without extra driers, you have fundamentally changed the product into the oil/varnish mix we would often call Danish Oil. Even when cured this mix is still quite soft compared to varnish which is why the directions for oil/varnish mixes call for all excess to be thoroughly buffed off the surface after a short penetration period.

As far as dust goes, the somewhat faster curing of wiping varnish is of some help, but as far as I am concerned never really enough for fine furniture. So for that, if I have to use a varnish, I just bite the bullet put on three coats of brushed on varnish, knowing that I will have to rubbout the final surface sufficiently to remove the dust while achieving the desired sheen. Either that, or I just use shellac for my final finish with much faster cure, much less dust problems, and easier rub out for all that.

[Cliff Rohrabacher]

Interesting. I have yet to try a rub out.
Is it difficult on complex geometries and small pieces?

I've seen people talking about steel wool followed by wax but that dosen't sit real well with me. Not that I think it's bad but, rather I think I'd prefer that the actual finish does all the talking.


Ive done some reading about rubbing out a finish. After the initial progression of abrasives to level the surface most folks talk about rottenstone and pumice.
However I should think that a good Auto-finish abrasive would be better yet still since auto polishes are exceptionally high sheen.

I may try some.

[Jim Becker]

If you really want to try the rubbing out stuff, abandon the polyurethanes and work with a "regular" alkyd or phenolic varnish product, Cliff. The chief property that poly was developed for was abrasion resistance (for floors). Rubbing out is abrasion. Further poly is softer in the scope of things and that also affects the quality of surface you can get by rubbing it out. The harder the finish, the better it will work for this activity.

[Cliff Rohrabacher]

[..]rubbing out stuff, abandon the polyurethanes and work with a "regular" alkyd or phenolic varnish product,

The urethane I'm using is an alkyd Minwax urethane. It's takes for ever to fully cure up and become hard. It's usable within 24 hours but over the course of a month or two the finish gets harder and more resistant to little dents and scratches.

Don't think I've ever used a phenolic.

I have some "Mothers polish" that I will try on a sample piece.

I got some Japan drier and added just a touch to my thinned wiping urethane (I used a drinking straw and pipped up about 3/4" into the straw). It really makes a difference in dry time.

Within about half an hour maybe 20 minutes the finish was tough enough that dust wouldn't settle into it. I'll see what it looks like in the morning.

[Jim Becker]

An example of a phenolic resin varnish is Waterlox. An example of a non-poly alkyd varnish is Pratt & Lambert #38. (which is also soya oil based, instead of BLO, and has a lighter color shift) Urethane resins are added to a finish specifically to impart abrasion resistance in most cases. Note that polyurethane varnish shouldn't be compared to two-part urethane finishes used in a professional setting...a little different animal to the best of my knoweldge.

[Cliff Rohrabacher]

I have been wanting to get some P&L #38 exactly because it's a bit brighter.

I've applies about a thousand sq feet of two component urethane. It is it's own unique thing. And it's so thick plasticy and rubbery that I don't imagine that any amount of rub out would do anything but mess it up.

I did an out of doors 15 year old spruce deck with the stuff. It has been like magic it is so good and tough. But for furniture, I don't think that particular product would serve - ever.

[Jim Becker]

Yea, the P&L #38 is really nice stuff. I've only used it once a few years ago because I generally stick to water bornes, but I was very, very pleased with it. It is good for brushing and you can quickly make a very nice wiping varnish with it by thinning 50/50 with Mineral Spirits or Naptha. I believe that Varithane has a soya oil based product, too. I seem to recall some ads for it awhile back.

[Joe Cunningham]

Cabot has an alkyd varnish too. Found it at my local Ace hardware while out looking for P&L (still haven't found anyplace that carries it locally).

I am using it on a computer desk I am finishing--sad to say, I got teh desk at one of those 'unpainted furniture' places. My woodworking skills trail my finishing skills by quite a large margin.

So far the results have exceeded my expectations and the cost is much lower than Waterlox--I thin it a bit with mineral spirits and the Cabot flows great.