My pore filling

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Redbloke1956
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My pore filling

Post by Redbloke1956 » Tue May 19, 2020 10:54 pm

Hi to all, long time follower but first time poster.
I have fairly recently started “building” guitars after seeing a few impressive specimens that my neighbour built. My plan has been to build something halfway decent as a birthday gift for my brother, my first prototype (with low cost timber) was a disaster that has taught me a lot.
One of the tasks that I hated was pore filling with Bote Cote (I also broke out in a rash from use) so I tried several other methods without much luck.
On my second guitar I went back and persevered with the Bote Cote for the neck but dreaded the thought of doing the back and sides of the body, after pore filling the neck I proceded to spraying it with Mirotone 3220...I was in love!
I found the Mirotone so easy to work with that I tried an experiment, I applied two brush coats of straight Mirotone on the back of the guitar, allowed them to dry for 48 hours then lightly sanded with 320 grit ....PERFECT pore filling!
I then applied about 10 light coats of 60/40 thinned Mirotone, left to dry for a fortnight, went over the whole back with a card scraper then 320 grit, 500 grit, 800 grit, 1000 and 3000 wet and dry.
This afternoon I hit it with my orbital buffer and the finish is more than I could possibly have hoped for, I can’t wait to buff with the fine compound.
Many, Many thanks to all on this forum (And my neighbour) for the ideas and inspiration...so far so good!
73FDB339-1760-4EEA-BAA6-9DF0B9CD285C.jpeg

seeaxe
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Re: My pore filling

Post by seeaxe » Tue May 19, 2020 11:37 pm

That looks OK......just kidding that looks amazing.

FWIW the Mirotone guy told me it can be used as a seal coat and no more than 4 coats total - but whatever you did keep doing it.
Richard

Redbloke1956
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Re: My pore filling

Post by Redbloke1956 » Wed May 20, 2020 6:00 am

Thanks Richard, I would be interested in the thinning ratio recommended to you, that could be the difference?
I followed the ratio of 60/40 with 10 total coats as recommended by Allen R. McFarlen in the tutorials.

Kev

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Allen
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Re: My pore filling

Post by Allen » Wed May 20, 2020 6:28 am

In deep pores using this method you are going to experience some serious sink back down the road as the lacquer continues to dry. And that process of drying / shrinking never stops with a solvent based lacquer.

That's why when builders are serious about dead flat and high gloss finishes that last they go with pore fillers that pack those pores with a product that isn't going to move or shrink.
Allen R. McFarlen
https://www.brguitars.com
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Bob_H
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Re: My pore filling

Post by Bob_H » Wed May 20, 2020 7:37 am

Allen wrote:
Wed May 20, 2020 6:28 am
In deep pores using this method you are going to experience some serious sink back down the road as the lacquer continues to dry. And that process of drying / shrinking never stops with a solvent based lacquer.

That's why when builders are serious about dead flat and high gloss finishes that last they go with pore fillers that pack those pores with a product that isn't going to move or shrink.
I am very interested in the issue of whether to use a seperate pore filler, or not. I was thinking of using shellac as a poor filler as per the approach described at http://www.stansellguitars.com/construc ... lac-finish. Allen, do you think the shellac likely to yield a different result to the Mirotone? Or is it more a case of technique? Very interested in views before I interfere with the fresh body of my current project.

BTW - lovely finish Kev - I will be really interested to see how it holds.
Bob Holbert
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Allen
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Re: My pore filling

Post by Allen » Wed May 20, 2020 8:01 am

If you are using pumice with the shellac then you can get very good results. Though it is very time consuming. It's the first step in a full French Polish finish.

The pumic is inert and the shellac binds it. You still need to leave an appropriate amount of dry time to get the alcohol fully evaporated. That of course depends on your environment and relative humidity, and how large those pores are to start with.

I used this method for about a year but it was taking far too much time when you build as many instruments as I do, and my shoulder and elbow just couldn't cope with it all.
Allen R. McFarlen
https://www.brguitars.com
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Jim
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Re: My pore filling

Post by Jim » Wed May 20, 2020 12:22 pm

I've had Allen's experience with the pumice/french polish- amazing but hugely time consuming and hard work. Just purchased the colortone clear waterbased pore filler from stewmac- will let you know how it goes.

Jim

Redbloke1956
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Re: My pore filling

Post by Redbloke1956 » Sun May 24, 2020 7:48 pm

Hi Allen,
I have given your reply considerable thought and carried out some tests and observations, you are correct about the sink back but I think you need to take into account the time taken for the solvent to evaporate.
The amount of gassing off? Decreases exponentially over time, you mentioned in a post on use of Mirotone that you left the finish for approx two weeks until you could no longer smell the solvent, therefore leaving the pore filling for some time (two weeks?) before sanding/spraying should mean that the sink back is negligible...which is exactly what I have found so far.
Kev

Redbloke1956
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Re: My pore filling

Post by Redbloke1956 » Sun May 24, 2020 7:59 pm

Hi Bob_H, I have used the shellac and Pumice method for pore filling and found it works very well, my understanding of that method is that the Pumice acts like an abrasive on the timber that effectively “sands” out fine particles of the parent timber and mixes with the shellac to fill the pores.
While I think you can achieve a finish equal to the Mirotone, I don’t think the shellac is as durable as the Mirotone.
I have also fount the Mirotone finish incredibly easy to repair.
Kev

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Bob_H
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Re: My pore filling

Post by Bob_H » Sun May 24, 2020 8:58 pm

Thanks Kev. I’ve read about the use of pumice, but have yet to give it a shot. I’m also interested in non-spray finishes. There is a luthier in the US called Les Stansell (http://www.stansellguitars.com) who uses an interesting approach where shellac is used in flood coats to pore-fill as well as a brushed (not French polished) finish. The approach is documented on his site (http://www.stansellguitars.com/construc ... lac-finish) and there is a related YouTube video. The overall effect is quite lovely, and I believe he has been doing it for years. I’m considering giving this approach a go, and would be interested in hearing from anyone who has tried it. There are so many views on pore filling!
Attachments
D09613E9-774D-4567-8993-0EF489212710.jpeg
Shellac finish - photo from Les Stansell’s website
Bob Holbert
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peter.coombe
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Re: My pore filling

Post by peter.coombe » Mon May 25, 2020 3:14 pm

I have tried a similar method myself with shellac and have managed to get the best finish I have ever had or seen bar none. However, it always crazes after a few days or weeks and that sort of makes it impractical. I have re-done the micromesh, and it still crazed but took longer. Gave up in the end and now use Target Coatings EM2000 which can be brushed and will never craze. My finish procedure is detailed here - http://petercoombe.com/publications/jaamim11.htm
Peter Coombe - mandolin, mandola and guitar maker
http://www.petercoombe.com

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Bob_H
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Re: My pore filling

Post by Bob_H » Mon May 25, 2020 4:30 pm

peter.coombe wrote:
Mon May 25, 2020 3:14 pm
I have tried a similar method myself with shellac and have managed to get the best finish I have ever had or seen bar none. However, it always crazes after a few days or weeks and that sort of makes it impractical. I have re-done the micromesh, and it still crazed but took longer. Gave up in the end and now use Target Coatings EM2000 which can be brushed and will never craze. My finish procedure is detailed here - http://petercoombe.com/publications/jaamim11.htm
Thanks Peter - this sort of advice is very helpful - any chance of an australian supplier these days?
Bob Holbert
Canberra

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peter.coombe
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Re: My pore filling

Post by peter.coombe » Mon May 25, 2020 9:05 pm

No Australian supplier, I still use shipito.com.
Peter Coombe - mandolin, mandola and guitar maker
http://www.petercoombe.com

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