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Sanding Back After Pore Filling with Epoxy
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=21166		 Page 1 of 1
Author:  Pat Hawley [ Mon Feb 23, 2009 5:23 pm ]
Post subject:  Sanding Back After Pore Filling with Epoxy
Of the pore filling methods I've tried, I've had the most success with System III epoxy. The only thing I don't like about it is that it darkens the wood more than I would sometimes prefer. I assume Z-poxy is the same in this regard. So I tried on scrap the idea of filling the pores then sanding back to the wood to recover the original wood colour (while still leaving the pores filled). Couldn't do it. By the time I had sanded enough to get past the uneven blotchy look from the epoxy, I had sanded through to a bunch of new pores. Is there something I am missing here? How does one pore fill with epoxy then sand back to the wood?

Thanks,
Pat
Author:  Hesh [ Mon Feb 23, 2009 7:23 pm ]
Post subject:  Re: Sanding Back After Pore Filling with Epoxy
Here you go Pat my friend - I sand back to the wood with epoxy pore fill and it does not come out of the pores for me even using a ROS. Remember too that when I am speaking of epoxy I am speaking of System III "finishing resin", Z-poxy "finishing resin" and West Systems 105/205 epoxy glue. System III and Z-Poxy both make epoxy glue too which is not what I like to use but the finishing resins in these brands works great.

http://luthiersforum.com/forum/viewtopic.php?f=10117&t=20320
Author:  Fred Tellier [ Tue Feb 24, 2009 3:28 pm ]
Post subject:  Re: Sanding Back After Pore Filling with Epoxy
Hi Pat

I might be just lucky but my 1st attempt at epoxy filler is ready to lacquer, I scraped and sanded back to bare wood after the 1st coat and worked any low spots flat, one nice thing about the epoxy it really highlights the low spots. The second coat was easy to sand to an even wood color as I had dealt with the low spots on the 1st sanding. I sprayed a coat of shellac today on back and sides. I will uncover the top and do a final light sanding and cleanup and a coat of shellac and I will be ready to spray lacquer.

I have never had such an easy job filling grain, it has put the fun back in finishing. Buying a finish from Joe White was becoming a thought as I hated the grain filling mess.

Now I need to get a 2 wheel buffer and finishing will be almost enjoyable or at least my sore shoulder will be happy.

Fred
Author:  LuthierSupplier [ Tue Feb 24, 2009 3:52 pm ]
Post subject:  Re: Sanding Back After Pore Filling with Epoxy
Pat,
I'm actually using z-poxy now to fill the grain on a little all koa soprano uke. I'm on the 2nd coat of zpoxy now. To me the key was to use an old credit card or thin plastic to squeegee it on. Then after all is on evenly, I just take a thick piece of paper towel and wipe it all off very lightly. This basically leaves very little on the surface, and it dries much quicker. I was able to sand in 6 hours. I don't worry too much about getting every spot down to bare wood. A few little splotches are nothing to worry about. They will be covered by the final coat. Just use 220 grit very lightly on the first coat to level and get everything even, then on the 2nd coat I used 400 grit to sand level. Then on the final 3rd coat, I use the 50/50 zpoxy and Denatured Alcohol to wipe on the final coat w/ a paper towel, and use 400 grit very lightly to rough up the last coat before your finishing sequence. If you don't like the color of zpoxy, then you should just use the wood dust and shellac method to fill your pores. You will have to do this 2 or 3 times over a few days to get a really good pore fill.
Author:  Michael Dale Payne [ Tue Feb 24, 2009 4:19 pm ]
Post subject:  Re: Sanding Back After Pore Filling with Epoxy
LuthierSupplier wrote:
Pat,
I'm actually using z-poxy now to fill the grain on a little all koa soprano uke. I'm on the 2nd coat of zpoxy now. To me the key was to use an old credit card or thin plastic to squeegee it on. Then after all is on evenly, I just take a thick piece of paper towel and wipe it all off very lightly. This basically leaves very little on the surface, and it dries much quicker.


Ummm I would be worried about leaving fibers from the paper towel behind. Now with a lint free cloth this very well might be a good process
Author:  Pat Hawley [ Tue Feb 24, 2009 5:49 pm ]
Post subject:  Re: Sanding Back After Pore Filling with Epoxy
Thanks for the input guys. Hesh your tutorial inspired me to order some Z-poxy Finishing Resign and give it another try.

Pat
Author:  LuthierSupplier [ Tue Feb 24, 2009 6:13 pm ]
Post subject:  Re: Sanding Back After Pore Filling with Epoxy
Michael Dale Payne wrote:
Ummm I would be worried about leaving fibers from the paper towel behind. Now with a lint free cloth this very well might be a good process

Michael,
You are right, there are some fibers left behind, but since I do a light sanding with 400 grit, these are taken off with no problems. You can use a lint free cloth and that would be better, but either will work. I do use the thick commercial grade paper towel. If you use it to wipe off only before it gets saturated, then no lint is left behind.
Author:  Hesh [ Tue Feb 24, 2009 6:26 pm ]
Post subject:  Re: Sanding Back After Pore Filling with Epoxy
Great Pat I am sure you will do very well with Z-Poxy.

Some food for thought: Some folks will "slather" epoxy onto the guitar in large quantities and use a foam brush to rub it all around and pack it downward into the pores before removing the excess and moving onto a different spot. What throws people off IMHO and it threw me off too is this idea of the squeegee or credit type card used as a squeegee. The natural inclination is to be very concerned about using the squeegee and credit card as a squeegee and removing the excess from the surface.

I also think that folks new to the technique will get their mind blown by how cool the epoxy looks on the wood - much like a great finish so we tend to not work it into the pores moving onto the remove the excess stage too quickly.

But what's really important for an easy, successful go at epoxy pore filling is getting the epoxy down into the pores. So use those squeegees and credit cards or even a foam brush to mash the epoxy downward into the pores and only after doing this from all directions then finish up using a squeegee action at 45 degrees to the grain.
Author:  Mike OMelia [ Tue Feb 24, 2009 8:10 pm ]
Post subject:  Re: Sanding Back After Pore Filling with Epoxy
Fred Tellier wrote:
Hi Pat

I might be just lucky but my 1st attempt at epoxy filler is ready to lacquer, I scraped and sanded back to bare wood after the 1st coat and worked any low spots flat, one nice thing about the epoxy it really highlights the low spots. Fred


Fred, did you see my post about that very issue? I agree. Finds them low spots! I had no problem with the z-poxy coming out of the pores, or with coloration. When it is on, it is indeed darker, but that sands right off.
Author:  Fred Tellier [ Tue Feb 24, 2009 9:51 pm ]
Post subject:  Re: Sanding Back After Pore Filling with Epoxy
This talk about blotting the excess epoxy awoke some dormant brain cells and reminded me of using epoxy to sheet foam core model airplane wings. I was very concerned about weight of the glue, and since a very thin coating of glue is all that is needed I used to take the entire roll of paper towels and roll it across the surface. The towel would pick up the excess epoxy and when saturated I just removed a couple layers of towel and continued. This should not disturb the epoxy in the grain, I will try this on my next Z-poxy finish.

Its funny how many skills I learned in model building have come handy building guitars, probably patience being the most useful.

Fred
Author:  joel Thompson [ Tue Feb 24, 2009 10:35 pm ]
Post subject:  Re: Sanding Back After Pore Filling with Epoxy
I thik Hesh gives excellent advice on this one.

z-poxy is my mumber one pore filler whatever finsh i am using.

the trick is to really mash that epoxy into the pores.
a little goes a long way and i like to work on a small area at a time.

when you are done you should be left with a very light coat on the wood but the pores completly filled.
this means that you dont have to sand to excess later.

after the first you will see a few pores open unless you have done an excelent job with squeegee and this why the second coat is essential even if you think you have filled all the pores.

i think it seems that the problem you are having is that your are not getting the epoxy far enough into the proes.

if you only squeege in one direction you can leve tiny air bubbles in the pores that become exposed after sanding.

mashing down the epoxy in all direction forces the air out of the voids and make for a much better first coat.
then the second coat should be much easier just filling any pores you missed or exposed again through sanding.

i used to scrape the epoxy off becouse i like a scraped sefice but i have found that it can be easy to take off to much wood and expose the pores again sanding is the way to go after leaving as little epoxy on the wood as possable after squeegeeing (is that a word).

There are a few ways that work well for this filler but this is the way that seems to work for me i hope that some of this is of use to you.

i think i will give tracys method a go as i recon you could get alot of the epoxy off with the right cloth while still leaving the materiel in the pores,


Joel.
Author:  LuthierSupplier [ Wed Feb 25, 2009 1:20 pm ]
Post subject:  Re: Sanding Back After Pore Filling with Epoxy
Here is a shot of the back of this uke that has 2 coats of zpoxy and the final thinned coat
Attachment:
finalcoat.JPG

Notice the shiny spots below after 1 coat and sanding back with 400 grit. These spots are perfectly fine since they will be covered by the final thin coat:
Attachment:
closupsanded1.JPG
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