Official Luthiers Forum!
http://w-ww.luthiersforum.com/forum/

Stain front or paint back first
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10123&t=50827		 Page 1 of 1
Author:  1984 [ Sat Jul 21, 2018 8:37 am ]
Post subject:  Stain front or paint back first
I cant see any problem with doing it either way: staining the front then cover it up and spraypaint the sides and back of the guitar or the other way around.

But one thing I've learnt during my guitar building project is that there always is unforseen problems, so therefore i am asking. Should it work fine staining the front first, then spraypainting the sides and back?
Author:  Freeman [ Sat Jul 21, 2018 10:53 am ]
Post subject:  Re: Stain front or paint back first
As I recall you were going to bind your guitar, I assume with plastic. That should provide a good interface between the stained portion and the "painted" part - you can mask and scrape at the binding. When you say "spray paint" - exactly what product to you plan to use? What will be the solvent in your stain (alcohol, water, or something else)? Do you plan to shoot something over the stained part (clear maybe) - if so what? You may want to seal the stained portion with shellac or some other sealer (with nitro I might use vinyl sealer) to keep it from bleeding into other areas.

If it were my guitar I would probably proceed as follows: Prep the entire guitar. Mask the sides including the binding to the edge. I don't try to mask the thin part of the binding, normally you can scrape that better than you can mask it. Apply the stain to the wood. When I was satisfied spray a couple of coats of clear sealer over the top.

Pull the masking tape and scrape any stain from the binding. Mask the sides of the binding again, this time stopping at the side to binding line, fold the masking tape over the top. Mask the top. Shoot your color on the back and sides. Pull the tape and scrape any little bits where color got on the binding. Take all the masking off the guitar and shoot compatible clear over everything. You are going to have some edges where you masked and scraped, you want the clear to blend all of this together. Let it cure and do the final sanding and buffing.

Like any finishing question, one of the best ways to answer it is to experiment on some scrap.

This guitar had stain applied to both the top and back/sides, then some color mixed with the finish. I masked the binding but as you can see, it needed scraping after the color was applied. It also has bound f-holes, I masked the insides of the body but didn't even try to mask the binding itself - just scraped it back before shooting the clear.

Image

Image
Author:  1984 [ Sat Jul 21, 2018 11:05 pm ]
Post subject:  Re: Stain front or paint back first
Thanks. I will likely use alcohol based stain, but I can also go for water based ... maybe i should use a water based stain since I am applying shellac finish (which is alcohol based)? I dont think it will make any difference ...

And yes, the binding will keep the painted and stained areas appart.

I did have lots of troubles with the plastic binding thought, i had to use CA to get it on - it was the only thing that worked for me. I did get a fair amount of gaps - and these I filled with plastic scraps dissolved in acetone, however this introduced some tiny airbubles in places. I did try to fix this a couple of different ways and it did get better but not perfect.

I will try filling the tiny air bubbles with shellac and pumice. The binding is black, but they say that pumice will go transparent. I need to be carefull so that i only fill the plastic first and not the top - if i do i will get tiny plastic particles in the grain of the wood. Propably the best way of doing this is first to seal the front, then the plastic binding - work on them as two seperate areas.


Also, I am at the moment deciding if i want to grain fill or stain the front first. Today i am going to try to grain fill (shellac and pumice) a scrap piece and then stain it to see what looks best.
Author:  Freeman [ Sun Jul 22, 2018 2:46 pm ]
Post subject:  Re: Stain front or paint back first
Just a couple of random thoughts. First, you only need to pore fill certain woods - mahogany, rosewood, koa, etc. Woods like maple, spruce, alder, basswood do not have open pores and do not need to be filled. As I recall your body is basswood, neck is maple and I forget the top, maybe maple also.

Second, if you put shellac on the bare wood (either by itself or used as a pore filler) it will seal the wood from absorbing stain. In fact I do that sometimes - brush a little shellac on wood binding or something that I don't want to get colored by the stain. Therefore if you are going to stain, do it first.

Third, I've used shellac as an intermediate coat but never as my finish. I can't offer any advice there

Fourth, you mentioned "spraypaint" for the back and sides. There are lots of products that might fit that description - my only experience is rattle cans of instrument grade nitrocellulose lacquer. Other than that I can't offer any advice.

We talked about binding before and I commented that I had tried both acetone cements and gluing by putting CA in the groove and then trying to install the binding. I have settled on installing the binding dry, taping it tightly in place and then wicking thin CA into the interface. Sorry you had so much trouble with yours, but honestly binding is one of the hard parts of building.

If you have gaps and the binding is black you can use black CA to drop fill small gaps. Be very careful with CA or any other binding glue - if you get it into the wood it will show up under finish and probably keep your stain from being absorbed into the wood fiber. Sand and scrape every bit out of the wood itself. I have never tried filling with shellac and pumice - I always either use lacquer or CA for filling

Definitely experiment on scrap.
Author:  1984 [ Mon Jul 23, 2018 2:16 am ]
Post subject:  Re: Stain front or paint back first
Freeman wrote:
Just a couple of random thoughts. First, you only need to pore fill certain woods - mahogany, rosewood, koa, etc. Woods like maple, spruce, alder, basswood do not have open pores and do not need to be filled. As I recall your body is basswood, neck is maple and I forget the top, maybe maple also.

Second, if you put shellac on the bare wood (either by itself or used as a pore filler) it will seal the wood from absorbing stain. In fact I do that sometimes - brush a little shellac on wood binding or something that I don't want to get colored by the stain. Therefore if you are going to stain, do it first.

Third, I've used shellac as an intermediate coat but never as my finish. I can't offer any advice there

Fourth, you mentioned "spraypaint" for the back and sides. There are lots of products that might fit that description - my only experience is rattle cans of instrument grade nitrocellulose lacquer. Other than that I can't offer any advice.

We talked about binding before and I commented that I had tried both acetone cements and gluing by putting CA in the groove and then trying to install the binding. I have settled on installing the binding dry, taping it tightly in place and then wicking thin CA into the interface. Sorry you had so much trouble with yours, but honestly binding is one of the hard parts of building.

If you have gaps and the binding is black you can use black CA to drop fill small gaps. Be very careful with CA or any other binding glue - if you get it into the wood it will show up under finish and probably keep your stain from being absorbed into the wood fiber. Sand and scrape every bit out of the wood itself. I have never tried filling with shellac and pumice - I always either use lacquer or CA for filling

Definitely experiment on scrap.



Actually I did not find that shellac sealed the wood, i was able to apply dye afterwards the shellac only contributed a amber tone to the dye.

I did get acceptable results on the binding by sanding into it a curve. Actually quite good considering its my first time doing and that the 7mm binding i had really should have been 8mm.

The small air bubbles are filled with superglue i think, thats why its white in colour.

Image
Author:  1984 [ Mon Jul 23, 2018 2:18 am ]
Post subject:  Re: Stain front or paint back first
By the way, when sanding burled wood like this, do you move the pad in a circular motion?
Author:  1984 [ Mon Jul 23, 2018 2:24 am ]
Post subject:  Re: Stain front or paint back first
I think i will try to dye first, then seal the top. then try to fill the gaps in binding with pumice + shellac. i will try to put a bit of pumice in black dye (mixed in alcohol) before using it on the binding. If i am correct, the pumice will soak up the colour then the left over dye will evaporate quickly.


I did try to fill the gaps with thin superglue and then sanding the spot to get plastic dust into the holes, i did however not have much success with this and wont be doing it again - it was very difficult to remove CA spill afterwards. If my shellac methods works I wont have this problem.
Author:  Freeman [ Tue Jul 24, 2018 11:10 am ]
Post subject:  Re: Stain front or paint back first
Seems like you have a plan. My only two comments are that since I have a bottle of this in black and I know it does a really good job of drop filling voids in black I would use it on the binding

https://www.stewmac.com/Materials_and_S ... _Glue.html

Otherwise I have no experience with pumice or shellac so I can't comment.

With respect to your question about sanding burl - I probably would use a sharp scraper for most of my work and skip the coarse grits. I probably would sand more or less in the long direction of the body. I do see a lot of scratches in your photograph - those will show up under finish. Also, if that is veneer instead of a top cap it will be very thin and its pretty easy to sand thru.
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/