I’m practicing finishing techniques while my guitar is being shipped. I’m using flamed maple veneered plywood. I would like to exaggerate the contrast and have been applying a lighter color over a darker color to achieve that effect. I’m using water based dyes.
1) Does the color coat need to be cleaned or treated prior to next step? My colored samples have a chalky surface. Should I wipe with Naptha or something?
2) For fillers, do I apply before or after staining? If I apply before it seems it might require more sanding of the thin veneer, and maybe affect the way the wood absorbs the color? I read not to use sanding sealer - what fillers should I be using?
3) Besides Tru Oil, are there any other non-yellowing topcoats worth considering?
Thanks for your help. I tried searching but most results seem to be about nitro finishes, lacquer, natural finishes, etc.
Apply any grain fillers before staining, but you won't need them for maple veneer, only open pored woods like ash and mahogany.
You don't want to use any solvents on stained finishes or some of the stain will come off again and you could get a very patch finish. Any chalky effect will probably be down to raised wood grain. I'd just run over the surface very lightly with some P1000 or finer sandpaper. You only want the paper to remove the raised grain, nothing else.
To highlight, you'd normally use a dark stain, then rub down carefully with maybe P400 so that you've removed some of the dark stain and are showing natural wood, then apply the lighter stain on top. Without any rubbing back, you don't get such a contrast. But be careful sanding and remember that the veneer is only 0.5-0.6mm thick, so do not take too much off the surface.
Sanding sealer is a matter of preference, and it does help seal the surface of the wood to stop finishes sinking in over time. Some are just very thinned versions of clear topcoat, whilst some also contain fine filler material, so aren't as transparent. But you need to keep in mind any finish going on the top, and make sure that the sealer is compatible with the finish used, or it could react. So it's always best to use the same make and range of products if possible to ensure compatibility.
Note that 'lacquer' is a fairly generic term for any clear or translucent tinted finish you can see through, as opposed to 'paint', which is opaque.
Tru-oil will stain slightly yellow. Wipe-on poly is popular, as are acrylic and poly sprays. These will remain clear and won't tint yellow, though any clear finish will darken the look of the wood underneath (mainly as it stops surface reflections from the wood).
So, I think the ‘chalky’ is the dye - I think the water is evaporating before the die really stains the wood. Even after a week, if the surface gets wet at all the color comes off. I have a water based acrylic that is brush-on, and the brush gets plenty of color on it.
I get little bubbles in the clear coat. 2 or 3 different hardware stores mentioned letting the stain dry, so I think the dye is sitting on top, then getting wet again when I put finish on, and hence the bubbles trying to escape through the clear.
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