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I have a body assembled to the point of starting the finish prep. It has a spruce top and mahogany back and sides. The mahogany seems quite porous.

I done a bit of searching for techniques over the last several months but can't seem to finalize my schedule for getting this done. Thought I'd rough out my plan here and see if anyone can point out anything that I'm planning that will get me in trouble.


First, pore fill the back and sides with Z-poxy.

Second, seal coat the top with clear shellac.

Third, spray the sunburst pattern on the top and back, as well as shading the sides. The sides to be shaded darker at the neck, waist, and heel with the 'peaks' of the bouts remaining clear.

Fourth, scrape the bindings and purflings to remove the color.

Fifth, apply a top coat of clear shellac over the entire guitar.

Sixth, light sanding to level.

Seventh, Finish with KTM-9 per the methods I have typically used for a clear finish guitar.


So, it would be helpful to know whether or not this is a sound approach.

Not sure if seal coating the back and sides with shellac, over the Z-poxy, might be a good idea or not.

Also, whether it might be better to put multiple coats of shellac over the burst before sanding it back,

Would certainly appreciate any comments.


Thanks,

Mark

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A world without music would Bb.

I eagerly await some responses!!

Mark,

Be very careful with step 6! Easy to sand through the clear coat and remove some of your burst, making for a touchy repair. Make sure you have a very level base prior to shooting your color. If you don't and you shoot a very thin top coat, you more than likely will start removing color before you get the finish leveled. If you are building up a thick top coat, this doesn't matter as much.

Not sure what you are using for a color carrier. If you are using tints mixed with a carrier, shoot those color coats almost dry and build up very slowly or the color will run or puddle.

Good luck!

Ken

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http://www.casperguitar.com

I've never used waterborne finish. My experience is with Nitro, so there will be some differences in application method.
Mostly, the process will be the same.
I laid down three full wet coats of clear before doing the colour coats. After the colour was on, at least three coats of clear before daring to sand. If you sand into the colour, it will be pretty much impossible to get it even again. I would suggest you get at least half of your top coats on before levelling.
Last burst I did, I masked out the rosette & forgot to leave the inner ring of spruce exposed. Took a bit of time to re-mask & spray that area.
Otherwise, your plan sounds good to me.

Mark, I am very much a beginner at this, but I have done two bursts with pretty good luck. Both involved staining the wood first, then some color in the finish. Here is an old thread on a mandolin done with StewMac's old water based finish

http://www.kitguitarsforum.com/archives ... 65_0_7_0_C

and a Les Paul with tinted KTM-9

http://acapella.harmony-central.com/sho ... aul/page8#

On both instruments it was inportant to carry the top color to the sides and back. Dan Earlewine's book is good, as is Roger Siminoff's instructions for mandolins.

btw - where in WA are you (I'm in Wenatchee)

Thanks for the responses.

It looks like there are several ways to approach this, so I will need to spend a little more time researching before plunging into finishing the guitar. Of course I will need to do some test runs on scraps first!

Sorry, forgot to mention that I was thinking of using a Transtint/ alcohol mixture to apply the color. From what I have read and Ken confirmed, this seems to require application in light coats and allowing it to dry before adding coats.

Hey Keller, I am on the wet side, kinda rural, just East of Marysville. Think I'll PM you about my Wenatchee connections.

Thanks again,

Mark

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A world without music would Bb.

Please do. One thing to think of is that I've got four of the SM Colortone tints. You only need a couple of drops - it would be silly to buy a bunch if you don't need them. Would be happy to let you use mine.

Any you are correct, you can either satin the wood, tint the finish or actually paint the 'burst on (or a combination). Each has its advantages (and dis - of course). One huge advantage of tinting the finish is that if you don't like it you can sand it off. One big disadvantage is that you can sand it off.

If you do visit the dry side, look me up.

Mark,

I have applied diluted transtint directly to bare wood, which is my preference with curly or quilted maple. But when you already have the wood sealed, I don't believe you will want to apply diluted transtint. Maybe the alcohol will allow it to burn into the shellac, but I believe you will want to use some sort of a color carrier other than alcohol. I mix Transtint with EM1000 and EM6000 from Target Coatings. As you are using KTM-9, I would forgo the interim shellac coat (step 5) and just use the KTM-9 tinted with Transtint to lay down your color, then scrap your bindings and shoot a bunch of clear KTM-9 topcoats prior to leveling.

If I am doing a light tint, I just mix the color with EM6000. If I am laying down a dark tint, I use EM1000. The EM1000 can really handle a lot of color, much more so than EM6000, which allows me to get the color down without as many coats.

Ken

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http://www.casperguitar.com

I have done exactly 2-1/2 bursts so take this for what it's worth. They did come out nice though. My technique is based on 1000 questions here and on other forums

It is very possible to get a nice burst by staining the wood directly....just not by me. The "safe" way to burst is to seal the wood entirely, I use just shellac as my woods aren't open pore, and then spray the color on top of them. Doing it this way allows you the option of sanding back entirely to fix a mistake. The problem I have with staining directly is that the wood never absorbs the stain the way I intended it to and, it gets so sucked into the wood it's difficult to fix.

If you are spraying over a sealer of any kind, you must spray the color in a medium of some sort. I've done both shellac and target USL and prefer the USL. If you spray just in alcohol, it won't work well, even over shellac. The coats have to be way too light to keep from running.

Once you've got your burst the way you like it - DON'T LEVEL!!!! You will burn through.

One last tip - if you're doing a 3 color burst (e.g. I did black, amber and red) do the lightest color first, then the darkest and then blend them together with the in between color.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Here's a thread I started a few weeks ago:
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=35152

Halfway down I describe my process, but it's very similar to what you described, except that I used 1.5lb cut shellac as a vehicle for my color. Yes, I'd be very wary about trying to level your burst. I just wouldn't do it. After spraying my color, I shot two coats of 2 lb cut, then sprayed em6000 the next day, right over the bumpy burst. Built up six or so coats, then leveled. So yes, I definitely recommend putting a barrier coat or two of shellac between epoxy>color as well as color>finish. Just remember to avoid applying epoxy over shellac -- no bueno.

Here's a shot after finish rubbed out.

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Mountain Song Guitars www.mountainsongguitars.com

This is spruce on maple, so no pore filling. The majority of the 'burst was done with colortone dyes in water sprayed on bare wood, shellac sealed, then colortone in EM6000 around the edges to make more opaque. EM6000 clearcoats overtop (... don't level anything 'till half dozen clearcoats on).

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Dave
Milton, ON