Shellac Questions

Steve-atl

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I’m doing some testing with shellac. The picture is of a mahogany test board. I applied a wash coat of shellac and then the StewMac‘s Colortone grain filler. Next, I brushed on a few heavy coats of shellac and sanded it flat. By the time I sanded out the brush marks the shellac was pretty thin. So I tried to shoot a couple of coats to see if that worked better. I thinned out the 3-pound shellac I was using and shot a couple of thin coats.

Now I’m getting these tiny dimples in the finish they go pretty deep. I think they were bubbles.

So how can I avoid this?

The temperature was pretty warm maybe 75° and humidity he was somewhat high.

I sprayed two very thin light coats.

I wonder if I didn’t thin the shellac enough or was it to warm

Thanks
 

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You may have used sandpaper that is made with stearates. They are supposed to help prevent clogging, but they also cause dimpling. For spraying many materials the warmer, the better.
 
You may have used sandpaper that is made with stearates. They are supposed to help prevent clogging, but they also cause dimpling. For spraying many materials the warmer, the better.

Thanks

The photo is before any sanding.
 
I've found using multiple coats of 1 lb cut gives me much better results than the thicker cuts. It takes longer but works better.

The two coats I sprayed after sanding down the brushed on heavy coats were thin. It looked like a 1# consistency to me.
 
The two coats I sprayed after sanding down the brushed on heavy coats were thin. It looked like a 1# consistency to me.

I don't know much about spraying finish,I pad on lot's of coats of 1 lb mix and sand progressively finer.I polish the last coat with extra extra fine steel wool and "feed and wax" It gives me a nice deep, low luster finish,best for hiding "irregularities". I've not had problems with bubbling.
 
I don't know much about spraying finish,I pad on lot's of coats of 1 lb mix and sand progressively finer.I polish the last coat with extra extra fine steel wool and "feed and wax" It gives me a nice deep, low luster finish,best for hiding "irregularities". I've not had problems with bubbling.

That's roughly how it works for me, though I do the final polishing with automotive cutting paste.

But if I haven't filled the pores fully, shellac seems to preserve them as I build it up, i.e. the shellac doesn't flow into an fill the pores but rather covers everything evenly, preserving the pore profile. So it takes many coats and cutting back to get a smooth surface. These pits might be the legacy of unfilled pores.
 
Such dimples are common (as in, every job ive ever done) in the first coats
 
Such dimples are common (as in, every job ive ever done) in the first coats

That was sprayed on a surface that was grain filled and sanded flat.

I think I figured it out. I strained the shellac with an auto paint strainer, sanded it down and shot it again. It's a lot better.
 
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