Official Luthiers Forum!

This evening I applied the first "coat" of Z- Poxy on my guitar.

Its great to see the wood come to life under some finish but 1 hour on and I can see some pretty serious runs around the edge of the guitar and small ridges on the back (didn't do the soundboard)

I'm guessing that tomorrow when I try to sand these level I'll end up going thru to the wood in numerous places. If I then do a second aplication will these sand throughs leave witness lines ?

I imagine I'll probably be best off sanding the whole thing back to wood with 180 grit sandpaper and starting again - trying to do better next time !

I notice that on the neck where I used my finger rather than a credit card it seems to pretty even so I thoght I might try a similar aproach or maybe a small sponge (like you use for washing up) to apply it to the body and see if it turns out any better. Sound like a good idea ?

Thanks for your help

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Richard

Are you using the Zpoxy as a finish or pour filler?

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Lance@LuthiersForum.com

I would try using a scraper to remove the runs. Every time I have tried to sand a run level I always end up sanding too much and get back into the wood. The scraper works much better for me.

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Dave Rector
Rector Guitars

Thanks for the speedy replys guys !

So if I try to scrape / sand flat and go through to wood in some areas by mistake will it leave witness lines under the final finish ? (which is going to be FP ( shellac anyway )



Lance K - As a pore filler

Todd - Whats a " Bondo Aplicator " ?

Thanks

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Richard

I don't mean to answer for someone else, but I believe that the bondo aplicator that Todd mentioned is the flexible spatula type of applicator for auto body filler. It lets you squeege (sp?) the stuff really well.

I am reading this with intest because my next step is to pore fill with the z-poxy, too.

Have just done my first zpoxy pore fill job and was having same problems. Thanks for the post and helpful replies.

Credit cards, plastic hotel keys, etc make very suitable substitutes.
Tom

Thanks for the replies - I'll try and get a plastic squeegee coz I'm realy not getting on with the credit card !

[QUOTE=Hesh1956] I use a clean rag wet with DA to clean up and/or smooth out any build-up of epoxy around the edges.[/QUOTE]
Hesh , Is this is while the ZPoxy is still wet ?

Thanks

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Richard

Like Hesh said an old credit card makes a great applicator. But, I always feel that the title 'pore filler' is a great clue as to what I'm aiming for. When I sand it back after application I always go back to bare wood leaving just the pores filled nothing else.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Colin,

So presumably you'd go along with my plan to sand off as stated in the original post. ?

If I do this how can I tell that I havent removed the filler from the pores ? (should I use a finer grit to stop the filler getting removed ? )

Do you still do the 50 / 50 coat or just strait on with the FP ?

Thanks

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Richard

Yes I would sand it back to bare wood, you may need to do the pore fill a couple of times but when I do it I make sure to squeegee of as much as possible leaving as little as I can to sand off. When I'm happy all the pores are filled it's straight on with the shellac, I don't do a 50/50 coat, as I said to me it's a pore filler, not a base coat.I only want shellac on my wood. On some woods that are marginal interms of pore size I don't bother at all just go at it with the French polishing.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Are you guys adding silica thickner to your epoxy mix? This additive will eliminate runs, sags and dips with the epoxy. I have been using System 3 epoxy with silica thickner for years with excellent results. The silica thickner is a fine glass powder that when mixed into the epoxy will bring the mixture to a consistency much like whipped cream. It looks white and creamy in the cup but is completely clear after hardening. To apply, I put a small dab on and then spread and squeegee with a 2.5" X 3" 3M Wetordry Rubber Squeegee (google that name) The squeege is very flexible and works great even on the backside of the neck. Any ridges or overlaps can be smoothed with a gloved finger or even a folded paper towel. The main thing to remember is that you do not need to completly fill the grain, only seal it. One or 2 coats of lacquer and your pores will be level because the pores will not absorb lacquer once they are epoxy sealed.

There are 2 magnificent benefits to using the epoxy: The color and figure of the wood is enhanced and the pores do not shrink and show with time after the finish is leveled.

Clean the squeegee with rubbing alcohol and save a clean one for wet sanding. You will cut your paper towel useage in half.

I'm using the system 3 with the silica thickener as well. I keep a clean paper towel and a container of DA at hand to clean up the ridges and runs. It works pretty well, even when working on a neck. I haven't found a sqeegee that works on a neck, so I use my finger (wearing gloves, of course) to spread the epoxy around.

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53% of all statistics are made up on the spot
http://driftwoodguitars.blogspot.com/

For you Aussie luthiers who want to try Z-Poxy here is where I got mine. Mail order takes about 3-4 days via Aussie Post.

http://www.barnesonline.com.au/product.asp?strProdFamily=Z-P oxy%20Glues

Thanks all,

Ended up sanding back to wood , the second attempt went on a lot better and today I will be sanding this then doing the 50 / 50 wash coat.

Presumably after that I only need to wait 24 hours before I can start french polishing. Should I sand the wash coat with 400 grit to give it a key for the shellac ?

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Richard

Ive just done a Zpoxy pore filling job on the IRW back and sides of my latest steel string. I put on two coats of Zpoxy and then had trouble sanding it back and ended up going back to bare wood in many places. I applied a wash coat of zpoxy and alcohol and then sanded back to bare wood again. The IRW is lighter sanded back bare than it would be if Id left a coat of Zpoxy on but the pores are well filled which is the aim of the exercise as far as Im concerned so Ive started with the French Polish job and so far its looking pretty good.

[QUOTE=Cachalote] Thanks all,

Ended up sanding back to wood , the second attempt went on a lot better and today I will be sanding this then doing the 50 / 50 wash coat.
[/QUOTE]

Like Colin and Martin, I only want pore filler in the pores, not as a coat on the whole surface. I feel I have much better control over the finish thickness this way. So if you are sure your pores are filled and not reopened by excessive sanding you can move on to the next step, forget adding more epoxy. In my case the next step would be spraying nitro.

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Rian Gitar og Mandolin

I've ended up going with a 50/50 mixture of system 3 epoxy & DA from the start, applying it with a balled up piece of cheesecloth dipped heavily into the mixture and spread liberally on the guitar with a quick back wipe to smooth the surface. I may have to go 1 extra coat this way but very little sanding is needed and it looks great. By the way this works perfectly for the neck and peghead, easy as pie!

Greg

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Gwaltney Guitars

Thanks for the advice everyone

In the end I decided to sand back to bare wood . For no other reason than I feel it seems easier to sand back 100% than not sand thru anywhere.

So today I started FPing !!!Cachalote39103.530462963

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Richard

[QUOTE=GregG] I've ended up going with a 50/50 mixture of system 3 epoxy & DA from the start
Greg[/QUOTE]
This may vary somewhat between brands of epoxy, and experience is the best indicator, but....

I've found that using more than a few percent of solvent to thin epoxy results in the cured epoxy having a 'rubbery' texture.
The WEST epoxy folks did some research on thinning epoxy. It's interesting stuff:
http://www.epoxyworks.com/14/ThinningEpoxy.html

Main points:
Warming epoxy is better than diluting with solvent if you need to reduce viscosity. It also reduces problems with outgassing and bubbles.
Shrinkage and 'print-through' problems are increased if you add solvent.
Only a small amount of solvent reduces the viscosity a lot.

John

I've used Zpoxy both ways prior to FPing...

1) sanding down to bare wood
2) Leaving a very thin, sanded smooth surface of ZPoxy

You have to make a commitment to either way. Having part of a surface sanded to bare wood while the remainder is coated will show an inconsistant surface and color once the final finish is completed. Either way works but I prefer to leave the surface coated. I get a smoother surface and I like the color and pop that Zpoxy imparts.

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JJ
Napa, CA
http://www.DonohueGuitars.com

JJ's correct....leaving patches of wood bare will lead to a patchy finish.

[QUOTE=JJ Donohue] Having part of a surface sanded to bare wood while the remainder is coated will show an inconsistant surface and color once the final finish is completed. [/QUOTE]

This will also be a problem if you sand throuh the finish and down to the wood later, and it is another reason I don't like the idea of leaving a layer of epoxy under the finish.

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Rian Gitar og Mandolin