Best Clear Grain Filler for Walnut Guitar?
I have to put a clear finish on my walnut guitar body. My luthier says I need to fill the grain with a clear product before applying nitro. I have been researching this, but as usual, I'm confused.
1. I thought I wanted a clear and colorless product, because I want the wood to show through, but now I'm reading that a little dye will make the grain pop out. Is that right? If so, what dye should I use?
2. I've seen lots of products recommended for filling. The two that stand out are shellac and epoxy. Shellac seems simpler, but a lot of people love epoxy, so there must be something to it. Which is better?
3. I believe my guitar has a few nearly microscopic holes in it where planing pulled on the figuring. I've seen superglue recommended for these holes. Is that the best way to go, or should I just keep applying filler until I get a flat surface? Also, will the little jars of acrylic glue work? They have nice thin application tubes that ought to be useful for applying tiny amounts of glue.
Careful consideration required
Before you go off and use this and that to seal, pore fill and seal again you need to know what your topcoat is going to be.
Something to realise is that a guitar finish a fair bit different from a furniture finish in that the desired film build is much thicker. These thick hard finish films are pretty sensitive to just about everything so you want to make sure that the adhesion between your sealer and top coats is excellent and that the two products pretty much behave the same way when it comes to temperature changes and wood movement. (look carefully into the topic of cold checking and lacquer).
Nitrocelluslose lacquer is a very common choice for the project that you have undertaken. If you too are going to use NC lacquer then I would strongly suggest that you choose your lacquer and then look to the manufacturer of your chosen topcoat for their recommendations when it comes to sanding sealers and pore fillers, solvents and rertarders etc.
If you are going with NC then the sealer of choice is typically a vinyl sanding sealer that uses the same solvent/thinner as the top coat.
Also look into tinting the pore filler. You can get a very nice effect by tinting the pore filler black or some other colour. Remove all filler outside of the pores prior to sealing and I think that you'd be very pleased with the results.
I'll mix and match to get the finish that I want but I would never just wing it on a project like yours unless I tested on scrap first. Often times not using the manufacturer's solvent/thinner with a given top coat will produce inferior results.
You're too far into the project to wing it now. Pal up with your local finishing supplier and you'll stick the landing.