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marcros

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I am finishing some ash. My plan was to fill the grain using a mixture of plaster of paris and powder paint, to enhance the grain, but leave the remainder very light in colour.

I understand that I need to raise the grain, the sand to 320. Seal using shellac, fill grain, and then further coats of shellac on top, de-nibbing between coats. Is shellac sanding sealer suitable for the first sealing, or do I need to make up a very light cut of french polish?
 

houtslager

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shellac sealer is usually prepared with some plater of paris in the mix, sometimes with talc powder. This allows grain to be filled with a neutral colour. Older GR's wre mixed with various pigments to match the end colour needed, usually in a thixotropic goo loke mix.

hth,

K
 

MIGNAL

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Test your grain filler on an off cut, just in case you don't like the appearance. Always a wise idea.
 

Sgian Dubh

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marcros":axwfkug1 said:
I am finishing some ash. My plan was to fill the grain using a mixture of plaster of paris and powder paint, to enhance the grain, but leave the remainder very light in colour.
This link might help as it describes a method I've employed several times over the years using plaster of Paris to fill grain. Slainte.
 

marcros

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Sgian Dubh":35799yjb said:
marcros":35799yjb said:
I am finishing some ash. My plan was to fill the grain using a mixture of plaster of paris and powder paint, to enhance the grain, but leave the remainder very light in colour.
This link might help as it describes a method I've employed several times over the years using plaster of Paris to fill grain. Slainte.
Thank you, it is actually that link that inspired me. I am planning to leave the background undyed and as pale as I can, but use the same vivid grain filling technique that you have- I was going to use a copper coloured powder paint if I can get some, or else a brown. On your article, you used a thinned pre-cat. I dont have the spraying facility- would shellac sanding sealer work to seal the background, or do I need to mix up a very light cut of polish, say 1/2lb cut?

Thanks
Mark
 

Sgian Dubh

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marcros":903php3l said:
Thank you, it is actually that link that inspired me. I am planning to leave the background undyed and as pale as I can, but use the same vivid grain filling technique that you have- I was going to use a copper coloured powder paint if I can get some, or else a brown. On your article, you used a thinned pre-cat. I dont have the spraying facility- would shellac sanding sealer work to seal the background, or do I need to mix up a very light cut of polish, say 1/2lb cut? Mark
Mark, I hadn't realised you'd got the idea from that web page. Yes, any thinned film forming finish will seal the wood, eg, shellac, varnish, etc. Avoid pure oil finishes like linseed oil and tung oil as they don't work well for this. The only other advice I'll give is use the same type of finish to seal the grain as you plan to use to finish the job, eg, varnish to seal and varnish to finish. Shellac sanding sealer works to seal the wood-- just add a bit of alcohol to thin it, and finish the job with shellac too. The idea of the thin sealing coat is to prevent the grain filler colouring up the denser summer growth wood too much, and concentrating it into the open pores of the spongy spring growth. Slainte.
 

marcros

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I have had a play tonight, and an experiment on some offcuts.

I couldn't get plaster of paris at lunchtime, or fine casting plaster. I did get some multi purpose filler from Jewson that you mix with water, so I figured it was much of a muchness. I also didn't get any powder paint. I planned to use a metallic copper one, but indecision about whether it would look good or dreadful caused me to procrastinate, which ran down the clock. So I used ground coffee (espresso grind, Italian). Through mainly luck, I achieved exactly the effect I was looking for.

What is the purpose of the plaster of paris? When I mixed the two, the grain filler was very light in colour, so much so it just looked a grubby white. I guess that paint will colour it more than coffee. Is it just because it is cheaper than using paint alone, or is there some other reason behind it. Would just using paint, or just using coffee be equally effective?

Thanks for your help everybody.
 

MIGNAL

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It's a grain filler. Paint or coffee won't actually fill the grain.
 

marcros

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it is doing something though, because the grain is coffee coloured. Is it just trapped in the grain rather than actually clogging it full/filling it?
 

MIGNAL

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I doubt that Coffee will fill the grain as well as Plaster of Paris. It probably doesn't bind as well as the Plaster.
 

marcros

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ah ok. I understand. It still fills the grain to a degree, but may not stay in there very well, or fill it as completely as a finer powder might.
 

thick_mike

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The plaster acts as an extender for the coating. It prevents the film from shrinking so much when it dries so that the holes in the grain stay filled when the coating is dry.

Mike
 
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