LMi Aqua coat clear wood grain filler. Warning Warning

Here here. I know it has driven me a little mad. The problem is that without a shellac backer, the stuff absorbs at differing rates on raw wood according to the different densities leading to patchiness which ain't pretty my friends. In other words, it doesn't penetrate evenly. Remember: Shellac is your friend always.
 
I can’t believe that I actually recall reading this thread ages ago but didn't make the connection until the instant I noticed my lovely chocolate koa turning green!

I put several coats of shellac as a base and sanded back the first application of Aqua Coat after it had dried (as per instructions). The second coat of Aqua Coat turned green all the spots where bare wood had been had been exposed. I didn’t notice until I was outside in the daylight, sanding for the next coat. I’ve been able to sand back through some of it but it's still showing in the curl stripes and this uke is already as thin as I dare go.

If I’d just applied a bunch of coats and sanded them smooth, I probably wouldn't have had an issue. It's where the wet filler touched bare wood and as sequoia says, it's a different blotchy shade depending on the grain. Yes, I tried it on a small scrap of koa, but I was seeing how well it filled pores and never thought of checking for colour shift. I’m surprised that none of my extensive googling on this product led back to this thread.

This tenor build seems to be taking the Murphy's law route - it's had the top removed and reglued, the binding done twice and the neck steamed off to reset it with a better angle.

Stay away from this stuff....I need a drink.

Edit: I've only read that an oil based top coat should go on this. Would it make sense to try sanding back to evenly bare wood, apply shellac and then tru-oil?
 
Last edited:
I've used Aqua Coat for several years and even wrote a review of it that appeared in American Lutherie. There is no need to "stay away from this stuff". You simply can't apply it directly to the koa wood. We used to apply naphtha based fillers directly to bare wood, but that is not usually done with water based fillers. Many, if not most, water base finishes, as well as Aqua Coat will give a greenish cast to the blacks in koa.. It is basically the only wood I work with, so I'm pretty experienced with the effects of fillers. Just apply your shellac or nitro wash coats before you use the filler. Do a decent job of keeping the 2 or 3 coats of filler level. No need to sand between coats. When you think you are done, sand the filler back and go on with your nitro or shellac.You won't have any trouble, even in the sanded through spots. If however you sand through and then apply a water base finish, you probably will get some greening. When the water base filler is used on the bare wood, the solvent base finishes can't wet the wood, which will give you a blotchy effect in any wood.
 
Thanks. I wish the instructions had been as clear as what you just said and had not directed to sand back between coats. I’ve managed to sand out the worst spots of green. If I understand you right, I can apply shellac over all without worrying about sanding back to bare wood everywhere. I’ll give it a final smooth and shellac it in the morning.
 
Top Bottom