Sunburst practice/test - What happened here?

[CarlM]

Just to compound your troubles, when you work on a carved piece it will react differently than the flat veneer because of the exposed end grain in the recurve. Also you might want to hand sand the final grits rather than orbital so the sanding lines follow the grain rather than the orbital circles.

I am going through the same learning curve, just a little bit further along having tried sunbursting a couple of instruments. It is not as straightforward as the videos make it look. Thank you to all the people offering instructional and suggestions here.

[Dale Ludewig]

If there's any chance you can spray, it makes a lot of this kind of go away. I hand apply a yellow wash over the whole instrument. To build up a glow underneath. And I use alcohol based for a normal sunburst. If I'm going to blue or some other color, that changes. After the undercoat, I go to a small spray detail gun. The advantage of spraying is that the wood isn't "sucking in" the color into the end grain like it is when you wipe it on. When you spray, everything gets the same amount. (All wood cells act like little straws. The end grain is the end of the straws.) Once it's sprayed on, I don't touch it. The dye is quite diluted and the build up is slow, kind of. When I want the edge to be kind of opaque, I add a little vinyl sealer to it. Then it acts like a toner and hides more of what's underneath.
It takes some experience to realize at this point, what you're looking at appears darker than it will after the finish is applied and smooth. This is because the surface had a million little shadows from the open pores and sanding. After the color is all on, a coat or two of vinyl sealer goes on, then sanded with 320. Bindings scraped. More sealer. More sanding with 320. Touch up where you sand through (you will). Then onto top coats.
John Hamlett's wiping techniques are to be envied.

[putnamm]

Thanks, Dale. I hate to think of just giving up on learning this technique just because it's difficult. I'd really like to learn. But I'm also wary of spending months on a complete instrument just to ruin it with a shoddy finish job...

Also, spraying anything is particularly difficult for me just given how our home is arranged and proximity to neighbors, etc. If I can avoid spraying I prefer to do so.

I tried another test piece, this time with 1/4 strength dye mix and really dabbed most of the moisture out. As soon as I wiped on the darker color it started blotching again. I guess that means most of the problem is in the preparation of the wood surface.

[sunburst]

I just re-read your OP and realized that you are working with veneer. When veneers are cut there is a thing called a nose bar used to help prevent checking of the veneer. It applies enough pressure to the veneer to cause subsurface compression throughout the piece so that the whole thing is like an inadequately sanded piece of wood.
You might get better results working with lumber rather than veneer.
(I have rubbed hundreds of successful 'bursts on laminated veneer banjo resonators, so it can be done, but trying "real" wood rather than veneer can't do any harm.)

[putnamm]

Ok. Thanks, John. I just resawed a piece of spruce I got at the lumberyard and am going to work on sanding and prepping that properly.

[HoGo]

When veneer is glued on under pressure the glue can penetrate and some parts or pores can be sealed and cause uneven staining as well.

[Dale Ludewig]

I was just about to post again and then John's post appeared. As usual, I agree with John. If there's compression going on from the machining process, sanding isn't going to make it go away. You could try steaming it, with a steamer like you'd use for clothes wrinkle removing, waiting for it to dry completely and then sanding. The steaming could swell the wood back up.
Are the pictures you're posting after the wood is completely dry? I've had luck when something looks like these pictures by hitting the wood with a heat gun. Paper towel in the other hand, and when the dye boils up out of the wood, wiping it off. The dark areas in these pictures all look like the ends of the little straws that wood is.
Remember the little wood straws/ end grain analogy. It's exactly what we go for to accentuate the curl in curly maple, or the quilt in big leaf. We wipe the dye on, let the end grain soak it up, and then try to wipe all the dye back off. But we can't get it out of the ends of the little straws. So it enhances the curly effect.
As to sanding prep, I don't sand past 150 grit before staining spruce. On maple, it depends on how much I want to see the flat grain/end grain effect. The finer wood is sanded when you're going to apply dye by hand: the sides (not end grain) of the wood cells are kind of like being polished so less little channels for the dye to lay in. You can't sand the end grain holes to the same effect, because you can't make a hole shiny.

[putnamm]

So it sounds like if I want to practice for real I'm just going to have to carve some tops and backs for practice!

[Dale Ludewig]

That's pretty much it. It's all practice, no matter how many instruments you build. Like John Denver said on one of the Circle Be Unbroken albums, when asked if this was the real take or a practice, he said "it's all practice". But at some point, you have to wade in and like the rest of us, finish up an instrument you know isn't perfect. Then you start the next one.

[CarlM]

So it sounds like if I want to practice for real I'm just going to have to carve some tops and backs for practice!

My first practice pieces were not full tops of backs but scrap pieces of board that I carved a recurve over part of it and arched some of the rest of it depending on how big the board was. The recurve is the hardest area because of the change from end grain to flat then back. I also have a couple of tops that I carved too thin. Rather than firewood those have become sunburst practice pieces. One of them has been resanded several times though I am getting close to where it won't work any more.

My tops have been cedar so far so I can get boards to practice on for it and the maple. I was able to find some spruce board stock at a lumberyard as well to practice on.

[putnamm]

The latest. Thin coat of shellac, 48 hour cure, half-strength Amber, wait 48 hours then apply color.

I'm working on a couple of mocked up top plates to practice on.

[putnamm]

At risk of becoming the forums' most notable nuisance, I had another thought I would like to pose to you all... :-)

I am taking some advice that a number of folks provided and using very diluted solutions of dye. I am using the liquid TransTint dyes dissolved in pure grain alcohol, and I am mixing at a ratio of four (4) drops of dye per one (1) ounce of alcohol.

When I initially wipe on a coat of dye it is almost entirely transparent. Compared next to one another, the different colors are obvious. It's not that there is no color to it at all. But it is extremely, extremely thin on color.

As a result, I apply other, multiple coats to begin getting close to the tint that I want. I'm usually doing this fairly soon after applying the preceding coats. This is all being done in the same session. In previous applications, the blotching began to become apparent fairly soon after I started--maybe the second or third coat. With the piece posted above (that included a wash coat then an amber coat) I had gotten to seven or maybe eight applications of the dark dye when I noticed the spotting/blotching and decided to stop. (By "decided to stop" I mean "threw down my rag and shouted a string of expletives that would make Hank Williams blush...") And the spotting/blotching wasn't nearly as bad or concentrated as previously.

So firstly, it seems to me that the shellac wash coat at least holds off and disperses the collection of dye in places...

But secondly, is it possible that by using a thinned out solution and thus having to apply half-a-dozen or more coats I am exacerbating the problem? In other words, the numerous multiple coats cause the dye to congregate due to repeated covering? If this is the case, then wouldn't a single or maybe two coats of a darker solution be warranted?

Appreciate all the direction everyone has already given. And I fully expect the best answer to my woes is, "Just keep trying different things until you figure it out." If that's the case, so be it. But I thought I'd run this by everyone here. Thanks.

-Mark

[Bill McCall]

Is that a plywood board? I think testing on a like sample is the best.

And I also think a 4x30” board, stepped off per coat, is the way to track the changes each coat makes. You’d get 15 coats in 2” steps, which is probably enough.

[putnamm]

Thanks, Bill. I'm using a "project board" also referred to as a "veneer" (though I'm not sure that's entirely right) that I had as a spare on my wood rack. I think I bought it at Rockler or Woodcraft of something. It's maple, 1/4" thick and it's maybe 5" wide. I cut it up in to little test pieces. No plywood, though.

I'm going through the process now of carving some sample top plates out of some spare spruce lumber I had. Not top-quality at all, so I don't mind carving it up for practice. That's what I'm going to do next. Several folks here observed that because of the shape of an archtop and what that does to the cells/grain of the wood it's best to test on a "real" arched piece. I will try that next.

That being said, it seems the struggles I'm having are more fundamental--wood prep, dye concentration levels, etc. And I already cut up the "project board," so I'm continuing to put it to use.

[CarlM]

Appreciate all the direction everyone has already given. And I fully expect the best answer to my woes is, "Just keep trying different things until you figure it out." If that's the case, so be it. But I thought I'd run this by everyone here. Thanks.

How many trials have you run so far? In my case I ran about 15 trials on carved boards and a too thin scrap top before trying a real instrument. I may be a slow learner. I would sand them off and redo them over and over. And the first instrument still was not all that good. The second is a little better but not perfect. It is not as easy as some of these guys make it look on YouTube.

[putnamm]

I've used eleven little test pieces like those in the pictures. But as I wrote earlier, they're just small, flat pieces of maple. I'm going to carve and sand/prep some arched pieces and test on those for the real deal experience.

[i8dpeach]

20 year lurker. Hello everybody!!!

I did this exact test for figuring out application of Transtint water based dye, shellac sealer (Bullsye) and then Spirit Varnish recipe testing and french polish practice. It's great advice to carve up some scrap spruce and try out everything. I even tried airbrushing, how much contrast I can get, how it is by hand, both by hand and airbrush. What is it like mixing the stain with shellac.... spraying the dye/shellac mix. I found after a month of testing I feel pretty good now. Going for a late teens Gibson look here with a bit more contrast than I would put on an instrument.

Here is a pic: https://imgur.com/Xba5jpl

[putnamm]

Thanks for sharing, i8dpeach. That tint job looks beautiful. And it reminds me of my earlier question...

I am using the TransTint dyes at 25% strength (based on what I've read). The first coat of the dark walnut looks like I rinsed out a cup that previously held grape juice: You can tell it's off-color but for the most part it just looks like water. So how many coats of that, then? Thirty? Fifty? To get that dark color that you have it would take a very long time, indeed. And maybe that is, in fact, the process. It's just contrary to what I have seen others do.

[i8dpeach]

I think you're going to want 60+ drops in your mix.... or more. That helped me get the "impact" I was looking for with the Dark Walnut. You could also mix in some Black to help you get there but it does change the characteristic warmth of the Dark Walnut. I went 15 drops at a time to get where I needed to go with the contrast. I would suggest starting with the Lemon Yellow or Amber Honey all over as a base to work with. I let it dry and then use some more later on to blend it, reactivating the dried yellow that's already there. Maple is super fun and easy. The spruce is where I put my time in and have the most practice so far. An airbrush really helps in the end!!! Just little touch-ups, ect.

I also raised the grain multiple times and sanded back down so when I used the water dye it didn't effect it too bad. I like water dye because it doesn't react with the first sealer coat of shellac. FYI

[putnamm]

I thought I would post an update here. I've spent some time fashioning some arched plates from scrap pine. It's not fancy spruce or maple, but it's something to practice sunbursting on. I used a random orbital sander with a 1/2" thick foam pad and sanded them to 320 grit. Then I started practicing my sunbursting.

The image attached here is my first attempt. Clearly it's not perfect. But the food news is that there is no blotching!

I appreciate everyone's feedback and direction. I used all of your advice and videos, etc. I did want to point out one video that helped me a great deal, and that is Tomy Hovington's staining video from his Mandola build. His combination of verbal explanation as well as demonstration of his technique really helped me understand how this process works. I will try to find the URL and maybe post it here.

For now, here is how my latest attempt turned out...

[putnamm]

I thought I would post this image as a response to the comments that the wood might be the problem. You may recall that I was testing on a maple "project board" purchased from Rockler. It was suggested that perhaps the industrialized processes used to produce such boards may severely affect the wood. So I'm working on some milled lumber maple arched backs to properly test on...

But this was the last piece of "project board." I sanded it (almost obsessively) to 320. I then raised the grain and sanded it back using 320--twice. I then applied my first coat of dye, let that dry, and sanded THAT back to 320. And finally then I did a full sunburst application.

You can see there are still areas of significant blotchiness. I'm not really sure what else I could have done to prevent this.

Anyway, I just thought this might be of interest as follow-up. As I said I'm progressing with actual lumber-based samples, so we'll see how those turn out.

[sunburst]

I see a 'line' between lighter and darker coloring in you test piece. That can be avoided by always using a circular motion or other means of not leaving a definite line a the edge of your dye application. In other words, working your way around the plate edge by making little spirals with the rag does not leave a 'straight' line so the transition from dark to light is more indefinite.

[putnamm]

Thanks, John. Yes, I'm still working on my technique. My blending has gotten a little better but still could use some improvement.

I was mostly posting that latest image to get people's thoughts on the idea that the particular wood might be the issue (versus my deficient skill). But I will have a couple of maple backs to test on in just a couple of days. So I guess we'll find out!

[putnamm]

Looking at some of my test pieces, I wonder if part of my issue might be that I am getting the wood TOO wet? I understand that the alcohol in the dye evaporates and so should not cause the wood cells to expand our hold moisture. But looking at the profiles of my test pieces it is clear that the dye penetrated all the way through. This piece is 1/4" thick. So is it possible that my application cloths were just too saturated? Maybe next time I should dab a good amount of the moisture off on a towel before applying?

[hank]

It’s amazing that so many different techniques work well as long as they acknowledge and deal with the end grain exposure and product to product compatibility. My input is that no matter what finish you use with or without dyes do not sand using your fingers as the abrasives backing. This is especially important on softer woods like top plates. Bowl sanding sets made for chucking up in a drill work well here using them like a round sanding pad by hand with finer abrasives. These also work well as intended in a drill press with heavier grits when initially shaping the plate. 3” is my most used size for final hand sanding.
Watercolor paintings are unique in that the paint flows. Masters learn techniques to float and inject color into the water bath knowing the causal likelihood of its travel and spread. The final effect is guided by the artist and his knowledge of how to manipulate the flowing paint on a flat even surface. To transfer that knowledge over to your shading gradient on Spruce you need deal with the endgrain capillary effect on your stain or paint flow. Some are doing it by filling them with water while others are covering them with sealer.