Thixotropic grain filler - am I doing it wrong?

[barbrainy]

Or is it just a PITA to work with?

This is my first proper build.



Before:

1 piece swamp ash body, planned to receive a blonde translucent finish:




So, I use some of this (as all the previous products from the seller have been excellent, and getting dark timbermate grain filler here in the UK seemed stupidly difficult):

http://shop.rothkoandfrost.co.uk/Dar...g-p/fs5063.htm

Here's what the body looked like after a generous coat of it:



Today I begin sanding it, as suggested by the seller, 320 grit. Nothing happening. I go to a courser grit (80, I think), and even that is a major PITA to sand it back with - it clogs the sandpaper up within seconds, and when, after HOURS of sanding (and even trying using a random orbit palm sander) here's how the front is looking:





To get rid of the dark, dirty, muddy colour in the areas that don't show grain takes a HELL of a lot of sanding, and seems that I am basically back to bare wood now everywhere, the grain included, so presumably completely defeats the object of having used this grain filler?

Am I doing this wrong?

Did I put it on too thick?

Have I sanded back too far?

How should it look at this stage?

Do I need to start over with a different product?

Would timbermate be much easier?

[Colt W. Knight]

Holy Cow, 80 grit? 80 Is going to put scratches way to deep to fill with finish. Plus, its most likely going to sand past the grain filler and back to bare wood.

I am not familiar with the product you are using, but is there any way to strip it with something chemically and start over?

[dsutton24]

Well, my limited experience with it is that it's pretty awful stuff. You have to mix the heck out of it, apply it and rub it in vigorously, and wipe off the excess before it sets up, you should be able to see wood and grain. It's not meant to be applied like paint and allowed to dry, it appears that that's what happened here.

[barbrainy]

Originally Posted by dsutton24

Well, my limited experience with it is that it's pretty awful stuff. You have to mix the heck out of it, apply it and rub it in vigorously, and wipe off the excess before it sets up, you should be able to see wood and grain. It's not meant to be applied like paint and allowed to dry, it appears that that's what happened here.

Ah, that was the kind of thing I was preparing to hear.........

The instructions on it (and on the website) made no reference to wiping off excess.....

Bugger.


Sand the whole lot off and try again with something easier like Timbermate? (Despite that being tricky to get here for reasons that completely escape me....)

[barbrainy]

Originally Posted by Colt W. Knight

I am not familiar with the product you are using, but is there any way to strip it with something chemically and start over?

God, I hope so!!!

I will ask the seller. It did clean up from me and the thing I applied it with very easily with cellulose thinners....

[Colt W. Knight]

Originally Posted by barbrainy

Ah, that was the kind of thing I was preparing to hear.........


Sand the whole lot off and try again with something easier like Timbermate? (Despite that being tricky to get here for reasons that completely escape me....)

You can actually use Dry Wall Mud or Wall Joint Compound as a grain filler. It comes in white, but you can easily tint it to the color you want using water based dyes commonly available in craft stores.

After you get the old stuff stripped, You will need to finish sand through 220 grit. That 80 grit will leave some deep scratches, so I would sand 100, 150, 220. Then apply a sealer. Then grain fill. Seal again. Apply finish.

[barbrainy]

Originally Posted by Colt W. Knight

You can actually use Dry Wall Mud or Wall Joint Compound as a grain filler. It comes in white, but you can easily tint it to the color you want using water based dyes commonly available in craft stores.

After you get the old stuff stripped, You will need to finish sand through 220 grit. That 80 grit will leave some deep scratches, so I would sand 100, 150, 220. Then apply a sealer. Then grain fill. Seal again. Apply finish.

Thanks Colt, I have read LOTS of your other threads, as well as taking lots of advice and guidance from the seller I mention above, and already knew I would have to undo the deep sanding marks I will have made. I got so fed up with this filler that I assumed it would need me to start over (but you learn from your mistakes, and this is not un-fixable) so already planned to sand back to to a finer grit once I had got rid of the filler...

I have not noticed anyone else in all my other research (besides yourself) suggest sanding sealer before grain filler (I have a cellulose sanding sealer); and I have not just ordered a selection of timbermate grain fillers from the US (via a US friend of mine) - my thinking being that it's one of the most commonly used, and appears to be easy to use (I've watched some videos as well as reading threads); so even with that, you still recommend sanding sealer then grain filler then sanding sealer again?

Thanks for your help, and for how promptly, on a Sunday too!!

[Colt W. Knight]

Originally Posted by barbrainy

Thanks Colt, I have read LOTS of your other threads, as well as taking lots of advice and guidance from the seller I mention above, and already knew I would have to undo the deep sanding marks I will have made. I got so fed up with this filler that I assumed it would need me to start over (but you learn from your mistakes, and this is not un-fixable) so already planned to sand back to to a finer grit once I had got rid of the filler...

I have not noticed anyone else in all my other research (besides yourself) suggest sanding sealer before grain filler (I have a cellulose sanding sealer); and I have not just ordered a selection of timbermate grain fillers from the US (via a US friend of mine) - my thinking being that it's one of the most commonly used, and appears to be easy to use (I've watched some videos as well as reading threads); so even with that, you still recommend sanding sealer then grain filler then sanding sealer again?

Thanks for your help, and for how promptly, on a Sunday too!!

I always apply Sealer first, grain filler, sealer again, then finish.

[barbrainy]

Edit: I am an idiot. I managed to type "I have not just ordered a selection of timbermate from Stewmac"

I meant I have!

Anyway, just for clarification (and to reduce the liklihood of more mistakes by me!), once wood stripped back totally to bare and sanded back to 220/320

1) Seal with my cellulose sanding sealer (I have an HVLP set up)

2) Sand back to flat with 220 grit? Finer? 320?

3) Grain fill with timbermate

4) Sand with 320 grit?

5) Sanding sealer again

6) Sand again?

7) Finish

[Shepherd]

You only need to seal the body prior to grain filler if you are using tinted filler. Otherwise, as you found out, it also stains the wood.
Some more info http://www.reranch.com/101a.htm
You should be able to remove the black by bleaching with household bleach and hydrogen peroxide if it's a dye based stain. If that doesnt work you can use swimming pool bleach which is much stronger.

[Colt W. Knight]

Originally Posted by barbrainy

Edit: I am an idiot. I managed to type "I have not just ordered a selection of timbermate from Stewmac"

I meant I have!

Anyway, just for clarification (and to reduce the liklihood of more mistakes by me!), once wood stripped back totally to bare and sanded back to 220/320

1) Seal with my cellulose sanding sealer (I have an HVLP set up)

2) Sand back to flat with 320

3) Grain fill with timbermate

4) Sand with 320 grit

5) Sanding sealer again

6) Sand again

7) Finish

That is how I would approach that. Sanding with 320 works really well.

Here is a grain fill thread I did using a waterbased filler

[barbrainy]

Thanks Colt, thanks Shepherd (that link to reranch really helped me get this process clear in my brain, and understand why I should seal first) - although I am annoyed at my mistake, I feel MUCH better now you have all set me straight!

[barbrainy]

Originally Posted by Shepherd

You only need to seal the body prior to grain filler if you are using tinted filler.
You should be able to remove the black by bleaching with household bleach and hydrogen peroxide if it's a dye based stain. If that doesnt work you can use swimming pool bleach which is much stronger.

Actually, I'm still curious about something here.

So I seal first......then use the tinted grain filler. Having already sealed the wood, how does the tinted grain filler then fill only the grain (after I've sanded back). Is it that the sealer is not 'thick' enough to fill the deeper holes in the grain, but is 'thick' enough to fill the smaller holes in the rest of the wood, thus meaning when I sand back the grain filler, the grain holes are deep enough to retain the filler, whilst the rest of the wood is not?

[Shepherd]

The sealer doesn't actually fill the pores. It just hardens the wood fibers which then cant absorb anything else. It's such a thin coat that most of it soaks into the wood and a couple of swipes with sandpaper will get to bare wood again. You could fill the grain with sealer but it would probably take a dozen coats or more.

[Old Bill]

Never do this to your new baby until you've practised a couple of times ,at least, on a piece of scrap timber or you could go bust trying.Best of luck mate.

[thepassivevoice]

Originally Posted by Old Bill

Never do this to your new baby until you've practised a couple of times ,at least, on a piece of scrap timber or you could go bust trying.Best of luck mate.

+1. Even after you have the filler problem resolved, you will likely want to use the filled scrap to test the color coat. There are many variations of blonde finishes and it may take some trial and error to get the one you want.

[barbrainy]

Originally Posted by Shepherd

The sealer doesn't actually fill the pores. It just hardens the wood fibers which then cant absorb anything else. It's such a thin coat that most of it soaks into the wood and a couple of swipes with sandpaper will get to bare wood again. You could fill the grain with sealer but it would probably take a dozen coats or more.

Ah, great, thanks. That's a really helpful explanation! So it stops all the wood absorbing the tinted filler, but the actual valleys/depressions in the grain itself can hold the tinted grain filler, which then remains when sanded flat over the the top.

However, I need to be very careful with stage 2 above, sanding the sealer?

Old Bill: good advice. I did actually ask the seller to send me some scrap swamp ash with the body for that exact reason, but it didn't happen. Should I ask him again, or try to find some scrap around that is a similar colour to the body??

[barbrainy]

Update (in case this info is useful for anyone else)

Cellulose thinners will strip the bulk of this filler off


(and Old Bill, the seller has very kindly sent me some swamp ash offcuts, without even charging me for the postage - www.guitarbuild.co.uk)