Spraying Varnish and Stain

[Dengue]

Hello, has anyone any experience spraying Cabots Gloss Varnish and Stain to get a nice smooth finish on bare timber?

Can you please tell me the recommended thinner, and how much the stuff out of the tin should be thinned?

All suggestions and ideas welcome :)

regards,

Dengy

[Jerry Thompson]

Spraying varnish will leave a mess over eveything what with the overspray. I don't know if you have water based alklyd top coats in Aus. but they would do the trick.
If you are going to spray WB dyes use the with water not alcohol or other solvent as the water base takes longer to dry and will penetrate better. This results in better color fastness.
I learned to spray dyes using clothing dyes obtainable @ food markets. I sprayed it on cardboard. This is cheaper than using wood dyes.
I let the dye dry and if the color is OK I hit it with a 1/2 pound cut of blond shellac then the top coat.

[Dengue]

hi, here is my test result for spaying Cabots Stain and Varnish gloss on a horizontal piece of plywood sanded to 240 grit. Not a really good result, but I don't know why !!

I used a HVLP with 2.0mm needle jet, and sprayed the stain and varnish straight out of the can without any thinning. I did 4 passes, two back and forth along the grain, the other 2 across the grain.

Based on the test results, do you think it worth pursuing with spraying this stuff with thinning, or should I open the jet and let more varnish out of the gun to try and get a thick wet film ( without any runs) ?

(The manufacturer says that it is not suitable for spraying, but won't say why)

regards,

Dengy

[Dengue]

Thought I would show the results of the first pass with the spray gun above. There are lots of little dark spots uniformly across the workpiece, presumably pigment?

If you look carefully on the first picture, you can see the tiny spots better on the paper underneath the workpiece, as by the time I got the camera out, the spots on the workpiece had started to become larger

Should this mean that there should be more stirring, or that the pigment has come out of suspension when being sprayed?

[soundman]

First thing that is obvious from your photos is that you are trying to spray a finish onto bare wood......first and major problem....nothing will help you till you fix this.

The timber will absorb the thinned finish unevenly...result blotchy.

If you are looking for a silky smooth finish you need to do more preparation in the way of a sanding sealer or severeal consecutive coats of finish sanding between coats till the finish is "choked out"....All the grain is filled with finish and the surface is flat and smooth

It is almost impossible to achieve a fully choked finish in less than 3 coats....of anything.

1st coat is absorbed, seals and hardens the timber surface, this allows more effecticve sanding, 2nd coat fills the grain and levels the surface, third coat is the finish.

But often many more coats are required to achieve the function of each coat.


Some one said I was a "recognised expert"....not so...this is basic information.

Anybody, thinking about doing this sort of stuff without some prior knoweledge should do themselves a big favour and buy Neil's (the bloke who provides this forum for us) "Pollishers handbook".http://www.ubeaut.com.au/book.html
It may not be the best, most detailed or comprehensive finishing book arround, but it is reasonably priced, easy to read, reliable and covers almost every issue I see posted on this section of the forum.
Available at many good woodwork suppliers or direct from U beaut polishes.

No vested interest.

cheers

[soundman]

Oh remember that ply is full of splits.
The plies are rotary cut from a log in a process not unlike peeling a potato.

When the curly slices are flattened and dried, it leaves them full of splits.

These splits can suck up finish...there can be a significant void behind a fine split that the finish will wick into.

those craters are where the finsih has been sucked down into such a void.

ya just have to keep applying product till those imperfections are filled.

This is why i prefeer to apply sealer coats with a brush, because it grinds the finish into the holes like spraying simply can not.

Ply takes quite some choking out.

cheers

[Dengue]

many thanks for this, soundman, there are some very valuable lessons for us all there. Will chase the book you recommend :2tsup:

[columnmn]

It doesn't look like you're getting enough clear out of the gun.

I have more experience spraying cars, but thought I might be able to help.

I'd thin your first coat down far more, so it sinks in more to the wood. Screw in the fluid adjustment all the way. Hold the gun from the paper the distance that you would normally spray (usually 6-8 inches) and give the trigger a quick squeeze and release. If anything comes out of the gun it should be very little and dry.

Turn the fluid out one full turn and repeat this procedure half a turn at a time until you are getting an even pattern and the paint is even in build.


Try a sample piece of wood, you will most likely have to back the fluid out one-half to one full turn to spray at the speed you want then fine tune your air pressure.
Now the gun is very close in adjustment, you should be able to lay the clear orange peel free with out running it. It might still require more fiddling to get right though.