Spray poly turns dull - help!

[Chris Colman]

I use rattle-can spray poly on turnings. It gives such a nice high gloss finish, and is sooo easy to apply.

Once in a while, with Cedar or Cherry in particular, I have noticed some grain areas turn dull after being sprayed. The finish is not being sucked up by the grain, it just turns dull - matte. If you spray more on, it just keeps turning matte in those areas.

I have tried wiping the pieces down before spraying with mineral spirits and other cleaners, but no change.

The only thing I have found that works is wiping on a coat or two of Tung oil/poly finish before spraying the poly.

Any ideas as to what is causing this, and how to avoid it?

[Mike Null]

I never tried spraying on a finish but I would be concerned that I wouldn't be able to get uniformity of coverage and that some of the spray might dry before laying on to the surface.

[Scott Holmes]

Chris,

If you like the gloss you get from poly in a can; you you will be blown away by the gloss that non-poly varnishes, shellac and lacquers will give you...

Poly is a bit less gloss than these harder finishes and these can be buffed to an even higher gloss. Poly can't really be buffed up to a higher gloss, it's too tough; not hard enough.

[Dennis OBrien]

Any recommendations for spray on non-poly varnishes, shellac and lacquers?

[Prashun Patel]

I still believe that the matte areas you're experiencing are just because the poly's being absorbed. The tung oil is serving to seal, which is why you get a quicker build. I bet if you keep applying coats, you'll get an even sheen eventually.

Another approach is to seal the wood with shellac before topcoating. Zinsser sealcoat wiped on is probably a more appropriate choice under poly u than an oil is; it will dry quicker and is less likely to cause adhesion probs.

In my limited time, I find that poly is a reasonable choice on turnings. A turning lathe makes controlled rubbing extremely easy on a lathe. Further, most of the turned pieces I see have very thin film finishes. I only see the aesthetic diffs between non-poly and poly varnishes at thicker levels. That's just one person's opinion though.

[Scott Holmes]

If you want to buff to the mirror gloss the harder finishes will out shine the tougher softer poly finish.

[Scott Holmes]

Chris what product are you talking about when you said: "Tung oil/poly finish"?

I know of no polyurethane varnish that is made with tung oil. Anyone else know of one?

[Pete McMahon]

Chris what product are you talking about when you said: "Tung oil/poly finish"?

I know of no polyurethane varnish that is made with tung oil. Anyone else know of one?

Frank Sutherland Wells advertises his "hard oil" as a uralkd tung oil wiping varnish.Through the grapevine he told a supplier it's just a poly resin. Quite a bargain at close to $100 a gallon!
Check out his "polymerized tung oil cleaner"at $82 a gallon.
What a scam. I had a client bring four gallons of his stuff by and asked if I wanted it. I told him he'd have to pay me to take it off his hands.

[Scott Holmes]

The lack of an MSDS sheet or a technical data sheet makes me think.... Hmmm... What's really in it?

[Chris Colman]

I am using a Formby product. I believe it is Tung oil with polyurethane in it too. I will check the can and get back to you.

[Scott Holmes]

Formby's Tung Oil Finish has ZERO tung oil and it is not POLY. The varnish was not even made from tung oil.

Formby's finish is an alkyd resin/soya oil varnish thinned ~70% with mineral spirits. Similar to Pratt & Lambert's #38 which is one of my favorite varnishes. I don't use Formby's products because I have a problem with their deceptive marketing. The product is a quality varnish but WAY OVER PRICED.

It's a wiping varnish pure and simple. He's made a a lot of money selling it as Tung Oil. In the past few years the label says it varnish they don't tell you the type; I did.

[Steve Schoene]

Sutherland and Wells do at least address the lack of a MSDS sheet, saying they use so little chemical drier that the amount is below the level of required reporting. They mention using a citrus solvent, presumably d-limosene, which itself may or may not require a MSDS. They have been around a long time, not necessarily a recommendation, specializing with polymerized tung oil products.

Also note that uralkyd is the resin of all the single part oil based "poly" varnishes. You will not find pure polurethane resin without going to the two part polyurethane finishes, which are pretty much a pro-only product given the toxicity of the solvents and materials. (One of the two parts will be an iso-cyanate.) Two part (2-k) polyurethane has considerably different properties than single part poly varnishes and shouldn't be tarred with the same brush.

[Karl Card]

I have had some problems with cedar turnings also. It seems that I can turn several pens and will use all kinds of wood, exotics, imports and also cedar. All the woods will take the lacquer just fine, except the cedar. Now this is not an all time thing just about 1 out 3 or 4 times that this happens. All the other woods will be ready for the second coat in 2 hours, not the cedar, it is still gooey and tacky etc. Still clear but very tacky. 2 days later I can check it again and still tacky, at this point all the other pens are ready to be put together and look wonderful.

The lacquer I use is Deft brush on oil base.

I recently tried the deft spray can "deftthane" on a persimmon bowl and man that stuff did take longer to dry but it is like clear glass... well super clear glass...

anyway on the cedar I assumed it was a chenical in the cedar that would not let the lacquer dry. As I stated this is just an assumption because I really have no ideal.

[Gordon Eyre]

I use MinWax gloss Poly thinned 50/50 (Poly/thinner) and applied with a white cotton pad or cloth. While the first coat or two will look a little uneven (dull/gloss) on certain kinds of wood, I do not worry about that at all. I just buff it lightly between coats with 0000 steel wool to even it out and then apply another coat. In my dry warm climate I can do this every two hours or so. I usually apply between 4 and 6 coats depending on the use of the project. After the last coat is applied I buff it once again with the steel wool and then let the project sit overnight and then apply a good furniture paste wax and buff it out with a soft cloth. It makes for a very nice even finish the feels great and gives off a soft even sheen or glow. By the way, I use the gloss Poly (MinWax brand) because it is a harder finish than the Semi-Gloss and can be easily buffed out to whatever degree of sheen you want with the appropriate material (steel wool, very fine sandpaper, pumice, rottenstone).

Your problem with the dull/gloss appearance sounds like an absorbency problem with the wood and will not be a worry as you apply more coats IMO. I also think that wiping the finish on vs. using a spray can is a better option for getting an even coat and is not difficult at all. I can probably apply a wiped on finish almost as quickly as you can spray it. Now if I had a large project and and a very good spray gun that would not be the case but even then with the clean up required for the spray gun I would not be far behind.