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Old 07-27-2021, 04:03 PM
donnyb donnyb is offline
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Default Staining/Sealing/Grain filling - Lacquer finish

Hi , I hope this is an easy question to answer. I havent done much acoustic guitar re-finishing , but plenty of solid colour and lacquer resprays.

Apparently when staining a sanded back acoustic guitar body, to ensure that the new stain goes on evenly and does not come out blotchy, grain filler is applied first (eg Feast Watson Grain Filler), and then the stain over the top of that. After that, the clear coats.

With the Feast Watson product, I assume its oil based as the can refers to using turpentine to clean up, and to clearcoat after staining with varnish, which I understand is also thinned with turps.

As I want to clearcoat this guitar with a solvent based lacquer like nitrocellulose , what grain filler can be applied and stained with a Prooftint colour that will be compatible with solvent based lacquer ?

Thankyou for reading.
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Old 07-30-2021, 09:48 AM
redir redir is offline
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Aquacoat is an excellent filler and it can be colored with water based stains. It works just fine with nitro on top. I have always stained before filling YMMV.

Traditional oil based fillers tend to stain wood a darker color and look great on mahogany. But Aquacoat is really good stuff imho and it's my go to filler now. It's very fast too.
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Old 07-31-2021, 07:54 AM
mirwa mirwa is offline
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Originally Posted by redir View Post
Aquacoat is really good stuff imho and it's my go to filler now. It's very fast too.
That is very interesting info and good to hear someone elses perspective, I have not liked aquacoat at all.

Possible that maybe I have been applying it incorrectly, I still have some in my shop, your reply and positive review has encouraged me enough to give it another go as its hard to find good grain fillers. Will read the directions maybe this time

Steve
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Old 07-31-2021, 08:44 AM
RoyBoy RoyBoy is offline
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I haven't used traditional oil-based paste wood filler in quite awhile, but from what I remember, when applied to raw wood, the coloring in the filler will stain the wood as well. With mahogany, this may get you the color you're looking for. Some people seal wood before grain filling to avoid coloring the wood, others sand back to bare wood after filling and then proceed with any coloring they want to do, it's all a matter of preference.

If you haven't filled mahogany before, I'd caution you that it takes more than one application of filler to get to flush. Some fillers tend to shrink back after leveling (oil-based definitely does).

When filling and coloring, one step not to skip is sealing in the color and filler with a sealer before top coating. Just make sure the filler is fully cured first. It's a lot of steps, but worth it in the end.
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Old 07-31-2021, 08:53 AM
RoyBoy RoyBoy is offline
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I haven't used traditional oil-based paste wood filler in quite awhile, but from what I remember, when applied to raw wood, the coloring in the filler will stain the wood as well. With mahogany, this may get you the color you're looking for. Some people seal wood before grain filling to avoid coloring the wood, others sand back to bare wood after filling and then proceed with any coloring they want to do, it's all a matter of preference.

If you haven't filled mahogany before, I'd caution you that it takes more than one application of filler to get to flush. Some fillers tend to shrink back after leveling (oil-based definitely does). To answer your compatibility question, you should be able to put nitro over any kind of filler, it's only in the pores. To ensure a good bond when mixing finish components of different bases, a lot of people get good results with water white acrylic sealer, it seems to bond with everything. For color, I avoid oil based stains unless I'm finishing with an oil based poly. Dyes are a better choice. Stains tend to lie on the surface while dyes soak into the wood. If you're spraying, you can add the color to your sealer or early topcoats.

When filling and coloring, one step not to skip is sealing in the color and filler with a sealer before top coating. Just make sure the filler is fully cured first. It's a lot of steps, but worth it in the end.
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Old 07-31-2021, 11:35 AM
redir redir is offline
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Originally Posted by mirwa View Post
That is very interesting info and good to hear someone elses perspective, I have not liked aquacoat at all.

Possible that maybe I have been applying it incorrectly, I still have some in my shop, your reply and positive review has encouraged me enough to give it another go as its hard to find good grain fillers. Will read the directions maybe this time

Steve
Yeah I think I pretty much followed the directions right off the side of the can. It's fairly similar to oil based... Apply, slather it all over, then scrape it off across the grain or on a diagonal. Then sand back to wood and repeat as necessary. I have not tried coloring it though. I would rather do that to the wood itself before filling.
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Old 08-04-2021, 11:25 PM
donnyb donnyb is offline
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OP here. Thanks for all replies, Ive been off line for a bit with a family health issue. All good now !

I have subsequently been told that Timbermate Natural (the unstained variety) is fine as a grain filler before applying any type of stain and clearcoat.

There's an online Video by Timbermate showing how you can mix all stain types into this product starting with ground coffee (the drinking type !) , and continue to change its colour by adding water, spirit and solvent based stains. I telephoned Timbermate and their tech man says it can be finished with any type of clear, including solvent based lacquers.

I mentioned in my OP that Id been told that staining the timber first can result in uneven absorption, and a blotchy finish. To rectify , I suppose that means sanding it back to find raw wood again, which sounds scary on a ply guitar body.

So, are there any downsides to applying Timbermate as a grain filler and staining its surface ?

Thankyou,
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