Mahogany Grain Filler?

What have you found that does a good job filling grain on Mahogany? I am a ways off from actually finishing my Ukulele but I have some Mahogany laying around and thought I would experiment a little.

StewMac sells ColorTone Waterbase Grain Filler. Has anyone tried this


Thanks

Yes, I have used it and I like it. It works... sorta. It will fill most of the grain but not completely. The way I look at it is it is a good start... Easy and forgiving to apply. Non-toxic. Easy clean-up. Is it the silver bullet to grain filling. Unfortunately no. I'm still looking for the perfect grain filler.

There is a thread I started on this stuff a few years back when it first came out. You could do a search.

sequoia said:

Yes, I have used it and I like it. It works... sorta. It will fill most of the grain but not completely. The way I look at it is it is a good start... Easy and forgiving to apply. Non-toxic. Easy clean-up. Is it the silver bullet to grain filling. Unfortunately no. I'm still looking for the perfect grain filler.

There is a thread I started on this stuff a few years back when it first came out. You could do a search.

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Thanks I will look for it

So far I have hated every water based grain filler I have tried. They take a million coats to fill large grained woods. They turn Koa green, a disgusting green at that. I have the best luck with Zpoxy. It's very forgiving on the mixing volumes as seems to work well for me. Comes in two tones, I like the lighter tone but it can be hard to find. I have also used CA and it works well too but I have had adhesion issues if it isn't sanded off everything but pores.

I have heard of shooting several coats of lacquer then doing the pore fill with the water based. I did that when I missed some pores on and area and that seemd to work ok.

All water based fillers will have shrink back problems, or move with big swings in RH. They will do anything from a terrible job to a reasonably acceptable one if you arent super critical.

Timbermate is an Aussie product that has been made for decades. Im pretty certain that is what the ColorTone product is and has just been rebranded. I used it a few times and while OK, it wasn't great.

I use a two part clear epoxy resin now called Bote Cote made in Brisbane. Don't know if you can get it overseas. Very forgiving on mixing ratio and easy to sand.

Doing a glossy pore-filled finish with a minimum of flaws will dramatically add to the total time spent on the project. It isn't necessarily a bad thing to give it a try but go into it with eyes open and with the understanding that more finish probably isn't going to improve tonal quality of the finished instrument.

I haven't had much success with water based fillers. They have a real problem with shrinkage and the relatively large pores in mahogany maximize that problem. Water based fillers also tend to deaden the appearance of the wood. This vid shows a piece of walnut sprayed with lacquer and buffed after being filled with TimberMate and then, on the second side, filled with CA. There's a big difference in appearance.

https://www.youtube.com/watch?v=66jS4Vz80mQ

I like CA and find it most useful on woods that have only moderate pores. For larger pores such as mahogany has, epoxy works better, at least for me. I've settled on System Three Silver Tip. This excellent vid by the estimable Jay Lichty covers pore filing with Silver Tip. It can recoated without sanding within 72 hours, which is helpful with mahogany because you might want to apply a couple of good coats to mostly fill the pores before doing any sanding. As far as final appearance of the grain is concerned, an epoxy pore fill will do about as good a job as CA. In both cases, it's a good idea to apply a coat of shellac before the topcoat.

https://www.youtube.com/watch?v=FXr9jYoikcA&feature=em-share_video_user

saltytri said:

Doing a glossy pore-filled finish with a minimum of flaws will dramatically add to the total time spent on the project. It isn't necessarily a bad thing to give it a try but go into it with eyes open and with the understanding that more finish probably isn't going to improve tonal quality of the finished instrument.

I haven't had much success with water based fillers. They have a real problem with shrinkage and the relatively large pores in mahogany maximize that problem. Water based fillers also tend to deaden the appearance of the wood. This vid shows a piece of walnut sprayed with lacquer and buffed after being filled with TimberMate and then, on the second side, filled with CA. There's a big difference in appearance.

https://www.youtube.com/watch?v=66jS4Vz80mQ

I like CA and find it most useful on woods that have only moderate pores. For larger pores such as mahogany has, epoxy works better, at least for me. I've settled on System Three Silver Tip. This excellent vid by the estimable Jay Lichty covers pore filing with Silver Tip. It can recoated without sanding within 72 hours, which is helpful with mahogany because you might want to apply a couple of good coats to mostly fill the pores before doing any sanding. As far as final appearance of the grain is concerned, an epoxy pore fill will do about as good a job as CA. In both cases, it's a good idea to apply a coat of shellac before the topcoat.

https://www.youtube.com/watch?v=FXr9jYoikcA&feature=em-share_video_user

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Thanks, saltytri I guess I forgot to turn on the notification to this post, so I am just seeing it.

The video by Jay Lichty is excellent. Thank you for posting it. Where do you get your System Three SilverTip? I did a little search and most places want to sell it in large quantities.

I get a quart/pint kit on Amazon.

saltytri said:

I get a quart/pint kit on Amazon.

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In Jay Lichty's video, it looks like he is using the Fast Hardner. Is this what you use? In the video, he said the Epoxy hardens enough to sand in 4 hours that does not seem all that fast

Just out of curiosity if Jay Lichty is just using the Epoxy as a grain filler why does he not just sand back to the wood. The Epoxy would stay in the grain and he would have the base he is looking for?

Fast hardener provides plenty of time.

Apply two coats with a foam brush. No need to sand in between per Mfr. specs up to 72 hrs.
Sand and apply again if the pores aren't well filled.
Don't sand too far. You'll know if you've gone too far if pores are opening up.
Better to leave an epoxy film here and there than to open a lot of pores.
It's very hard to sand a whole workpiece to perfection, i.e., epoxy only in the pores, all pores fully filled and no epoxy film anywhere.
Thus, a pretty well sanded surface often looks blotchy.
To avoid a blotchy appearance, the final coat of epoxy can be a thin wash coat that doesn't build much thickness.
SilverTip is pretty thin and can be thinned further with a bit of alcohol. As a guess, up to 10%. This helps it act as a thin wash coat.
Sand lightly.
One or two wash coats with shellac.
Proceed with finish.

saltytri said:

Fast hardener provides plenty of time.

Apply two coats with a foam brush. No need to sand in between per Mfr. specs up to 72 hrs.
Sand and apply again if the pores aren't well filled.
Don't sand too far. You'll know if you've gone too far if pores are opening up.
Better to leave an epoxy film here and there than to open a lot of pores.
It's very hard to sand a whole workpiece to perfection, i.e., epoxy only in the pores, all pores fully filled and no epoxy film anywhere.
Thus, a pretty well sanded surface often looks blotchy.
To avoid a blotchy appearance, the final coat of epoxy can be a thin wash coat that doesn't build much thickness.
SilverTip is pretty thin and can be thinned further with a bit of alcohol. As a guess, up to 10%. This helps it act as a thin wash coat.
Sand lightly.
One or two wash coats with shellac.
Proceed with finish.

Click to expand...

Thank you for all your input

My pleasure. The more nice ukes out there the better.

One thing you might know, but better safe than sorry: Not rubbing alcohol. Denatured works as a thinner but it's not good for you. I keep a jug of Everclear in the shop. It doesn't do any harm if you get some on your hands and it sometimes amuses visitors.

Yes I just picked up some Everclear, It definitely adds to my street cred

Be sure to read your individual product's instructions and specifications. I have used the 2:1 botecote that Allen uses for boat building and it is very forgiving of chucking on second coat without sanding while 5:1 mixes tend to be prone to amine blush which has to be sanded off or nothing will stick to it. Also be aware that Epoxy and PVA do not stick to each other.

saltytri said:

My pleasure. The more nice ukes out there the better.

One thing you might know, but better safe than sorry: Not rubbing alcohol. Denatured works as a thinner but it's not good for you. I keep a jug of Everclear in the shop. It doesn't do any harm if you get some on your hands and it sometimes amuses visitors.

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hahaha- I have everclear AND small 5cc syringes (for injecting glue into tight places) the syringes aren't a good look !!

saltytri said:

I've settled on System Three Silver Tip. This excellent vid by the estimable Jay Lichty covers pore filing with Silver Tip.

https://www.youtube.com/watch?v=FXr9jYoikcA&feature=em-share_video_user

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I picked up some Silver Tip. I applied the first two coats (on bare wood) with a squeegee and for some reason, it left an Orange peel look after it dried. Next, I tried a foam brush and it left tones of air bubbles. In Jay Lichty's video, he heats his drying room up to 75º or 80º. I thought this was to help in speeding up the drying time. but now I am wondering if the heat helps the epoxy flow out better. Do you let it dry in a warm room?

Thanks

Perhaps what you're seeing is due to the unusually porous nature of mahogany. It's got more air in it than most other woods that are used for instruments and some mahogany is more porous than others. You may be seeing "off-gassing" through the epoxy before it hardens. With your wood, a good tactic might be more and thinner coats.

It never flows like paint so it's never smooth. Ideally, each coat should be thin because: 1) It isn't cheap, and 2) the goal is to fill the pores and sand off the excess. Even with a squeegee, it is possible to leave too much on if the squeegee is used to push around too thick a coating. I'd try to work toward more and thinner coats. One of the advantages of SilverTip is that it can be recoated in a few hours without extensive sanding. So, put on a first coat squeegeed back to the wood. After a few hours, get the nubs off with sandpaper or, better yet, a card scraper. At this point, you'll probably see that the pores are not filled to surface level but that's OK. At least, the wood will be sealed. Apply another thin coat of epoxy. As Robbie O'Brien often says, "Rinse and repeat."

I haven't had much of a problem with orange peel or bubbles. I don't heat the workpiece up after application. An unscientific guess would be that abruptly changing the temperature could pull some air out of the wood.

A foam brush does work with some woods but may not be the best approach for your wood. There's no magic bullet for filling pores. It's all a PITA until you find products and methods that work for you and even then it isn't the best part of building. I've tried a number of materials and methods and now tend to use SilverTip on more porous woods, CA on less porous woods and various methods suited to particular situations.

Here's another version of the use of SilverTip:

http://www.acousticguitarconstructionforum.com/viewtopic.php?f=22&t=3062

I don't have any bodies in the fill stage now but here are two necks that are under way. The first is Spanish cedar, which has pores that are fewer and deeper than most mahogany. On necks, I apply the epoxy with a gloved finger with the goal of keeping it thin but the general approach is the same as with bodies. You should be able to see that the pores aren't yet filled to the level of the wood and will probably take at least a couple more coats to get it smooth. After these two coats, I'll level sand between further coats, probably with 220 to start.



This one is Honduran mahogany with two coats applied the same way as on the Spanish cedar.

Steve-atl said:

I picked up some Silver Tip. I applied the first two coats (on bare wood) with a squeegee and for some reason, it left an Orange peel look after it dried. Next, I tried a foam brush and it left tones of air bubbles. In Jay Lichty's video, he heats his drying room up to 75º or 80º. I thought this was to help in speeding up the drying time. but now I am wondering if the heat helps the epoxy flow out better. Do you let it dry in a warm room?

Thanks

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Can't speak to Silver Tip specifically, but most epoxies thin out with higher temperatures. They also cure faster.