Hand rubbed sunburst

[herickson]

Hi,

So as not to hijack a previous post, I started a new one. A couple of you have indicated that you do a hand rubbed sunburst (as opposed to spray). I'd like to do that for my #1, but have yet to work up the courage. I'll be doing a French Polish for the finish coat(s) as well. I've got my shellac mixed, but I'm a bit uncertain as to how to proceed.

Here's my current plan of attack:
1) practice, practice, practice (on scrap wood)
2) Sand to 320 grit or better
3) Fill wood with pumice and smooth. Is this needed for maple?
4) Mix a 2 lb cut of shellac
5) Apply an undercoat of shellac to seal wood grain
6) Mix colors. I'm using StewMac Colortone concentrate. Is it best with water or alcohol? Can it be mixed with shellac? Not sure what a 'finish toner' is?
7) Apply colors; I've heard it helps to keep everything as 'wet' as possible while doing the blending
8) After drying, apply a few 'very' light coats of shellac using FP method. Try to avoid streaking the colors.
9) Apply more shellac as needed, sand, re-apply, etc.
10) Final buff out.

Please let me know if this sounds right to you experienced folks. Any tips would be appreciated. Thanks so much.

-- Herb

[austin]

Herb,
You are close....
This is what I do (also a newbie approach so include a margin of error).
1. Sand to 600 grit (finer sanding=enhanced figure)
2. Check for pitting or gaps at binding
3. Wipe down with Naptha to check for missed sanding scratches and to clean any residual oils.
4. Stain entire instrument yellow or light base color.
5. Gradually layer in sunburst with darker and darker colors blending with alcohol on a rag.
6. Seal with bullseye spray shellac so as not to smear burst. (do your first coat or two very lightly!)
7. Brush on body coats of 2-3# cut shellac (I also add sandarac or copal for better durability) #I will usually apply 5-6 coats per day for a couple of days, waiting an 15 min to an hour between coats depending on the weather.
8. Let cure for a few days then level sand with 400 grit.
9. Final french polish OR, rub out with 3M Polishing compound and Meguires swirl remover.
10. Let harden for a week or two (weather dependent) #before fitting the bridge (be sure you don't want to move the bridge much, because at this point the varnish will still be damaged by the pressure of the bridge)

This is my "simple" approach.
#4 will get oil varnish, so this may all go out the window....
-austin

[sunburst]

Here's how I've done it for 20something years.

1.Sand to 220. That's all I need. Finer sandpaper makes no difference in the final finish I get, so, for me, is a waste of time. The stains will enhance the figure as much as anything else.
2.Check everything and fix it if it isn't right
3.Stain the whole thing yellow. Add some amber sometimes, depending on the color of the wood.
4.Sunburst
5.Clean bindings
6.Spray with lacquer. (multiple coats with sanding in between, 220 or 320 grit)
7.Let cure for at least a week
8.sand out to 1500 grit and buff.

here's how I do the burst on a back (the top is similar and the sides and neck are variations):

I use alcohol soluable stains. I have three jars on the bench with wide mouths and a rag next to each one. One contains alcohol, one brown stain, and one a very dark reddish brown stain.

The mandolin is already yellow. Keep it damp, not too wet with the alcohol, and stain around the edge about 2 or 3 inches with circular rubbing with the brown stain on it's rag.

Blend that into the center with the alcohol on it's rag.

Repeat until satisfied.

Stain around the edge about 1.5 to 2 inches with the dark stain, again on it's own rag and blend with the alcohol.
Again, repeat until satisfied.

Sometimes I touch up the edges and some of the nooks and crannies with an airbrush and some of the dark stain.


If the mandolin is too wet, you can get little water-spot-looking places in the stain. They show up as it dries and can be difficult to control. I've seen them in Loars.

I plan to varnish one of the mandolins that I am making now, and I don't plan to seal before I stain. I've never done it that way, so I don't really know how.
I'll probably spray on a very light coat of shellac as a sealer after the stain. A coat that is too heavy can bleed the stains onto your freshly cleaned bindings.
I might also try sealing with egg white if it works on a scrap.

[austin]

oh yeah, scraping....
I knew there was a reason I like black binding!http://www.mandolincafe.net/iB_html/non-cgi/emoticons/smile.gif
-austin

[sunburst]

austin, I wish it was that easy. My black bindings don't look as black if I leave the stain on them. They're sort of muddy looking. I have to scrape them too. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/sad.gif

[Luthier Vandross]

I use a touch-up gun to shoot the color to the edge, but then I go 'old school' and drag it back and forth (grainwise) with a cloth wet with alcohol.

Once I have the yellow, and the (insert color) on, I add a cap of black stain to the dark color, and touch a fine line, drag that, then darken it in once more at the edge, then seal coat.

I never touch that last stain with a rag.

M

[Dave Cohen]

There are a couple of details that I didn't see in this thread. firsst, you do not need to fill pores w/ spruce, cedars, redwood, maple, cherry, or other small pore woods. You do need to fill pores with many other larger-pored hardwoods, e.g., mahogany, any of the rosewoods, koa, walnut,... The second is adding a "ground" color to "pop" or enhance the figure of curly, quilted, or birdseye figured woods. I typically wipe on a solution of either honey amber dye or golden brown dye in alcohol, allow it to dry thoroughly, then sand back w/ 220 or 320 SiC paper. The dye penetrates more deeply in the part of the curly figure most oblique to the plane of the surface of the wood, and less deeply where the grain is parallel to the surface. When the surface is sanded back, the dye remains in the oblique grain, but is sanded off in the parallel part of the grain. Hence, the curly figure is accentuated. You can get some of this effect with a wash coat of 1 lb cut garnet shellac or (dewaxed) button lac, but it is more pronounced with a dye.

[sunburst]

Dave, I didn't mention the "ground" color because I don't use one anymore.
I get the same, or similar, effect from the rubbing of the stains.
As the stains are rubbed on, the oblique grain absorbs more stain while it is being wiped back off of the parallel grain to some extent.
If I were to spray the burst I would benefit from the "ground" color.

While I'm posting here anyway, as I think back, the 20something years that I mentioned earlier is not quite right. I don't think I sunbursted anything until about 1988.

[Luthier Vandross]

Sanding is part of dragging, that gets done after the first dark application on my stuff, and anytime I need to see more yellow.

The grain pops, maybe the first few didn't as much.. I'm getting better.

M

[herickson]

Thanks for all the replies! A few follow-ups if you would indulge me further....

So I don't need to fill any pores in maple; good to know. It didn't look like it would to naked eye but I wasn't sure once the thing got wet.

As for pitting or gaps around the binding (not that I would have any of that #http://www.mandolincafe.net/iB_html/non-cgi/emoticons/tounge.gif ) do you fill that with wood filler or something better?

The reason I had mentioned the undercoat prior to adding color, is I had thought the dye would tend to follow the grain lines in the wood (for the spruce top at least) and look irrregular; not so?

Once the color is on, you recommend a spray for the first few coats, so as not to smudge the dye. Has anyone tried without a spray? What I was thinking is to *very* lightly apply the shellac with a fob. I guess the colors would bleed but was wondering if it could be part of a continuation of the blending process. Just a thought.

You guys are a wealth of knowledge and experience. Thanks again for sharing.

-- Herb

[sunburst]

Pits around the binding:
If it's plastic binding, I usually heat it with a heat gun and push the pit or gap closed with a finger and let it cool. A little Duco cement drooled on top will seal it.
Other than that, after the first coats of finish, I fill them with stick shellac and a burn in knife.

Spruce grain lines:
A dye or stain will "reverse" spruce. That is, where the grain lines are darker in the unstained wood, they will be lighter in the stained wood. Violin makers and players hate this, but mandolin makers and players seem to accept it as normal.

FP over stains:
Don't know, haven't tried it.

[austin]

In my humble experience, you could probably brush a sealer over the dye/stain if your sealer and stain do not have the same solvent. My first experience trying to do this was not well thought out and I ended up having to sand out the muddy mess of stain I made and restain. Since then I have only sprayed my sealer coat so as not to smear my hard won sunburst. Remember to spray very lightly because it can still bleed if it gets too wet!

[Luthier Vandross]

If you are doing a varnish finish, brushing is surely acceptable... best with a badger brush, and shellac for the sealer.

I shouldn't eat so much hide glue, it keeps me up lately. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/smile.gif

M