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First time trying Target finishes. I have experience with Enduro Var and other waterborne finishes.

This poplar thinline style body was stained with Trans Tint (mixed in water). After brushing on a couple coats of the Ultraseal WB Shellac a stripe has appeared along the glue line in the lower bout area. No stripe up closer to the neck attachment.

Not the end of the world, I built this in poplar to try out some new work methods before doing a "real" build with nicer wood. But i would like to understand why this is happening so I can avoid it in the future.

Glue was Titebond 1. It does not look like the joint is separating.

The stripe seems to be only on one side of the joint, and like I said, does not run the full length of the body. This makes me think that piece of wood absorbed more glue than elsewhere, and therefore did not absorb as much stain, although the color looked uniform before the sealer was applied.

If that is the case I think there is no point in sanding it down and doing it over, as the same thing would probably happen again.

Anyway, if anyone has any other ideas about what happened, I would appreciate you posting them .

Thanks

If the line bothers you, and you have more coats of finish to apply, you could selectively place some stain on top of the existing finish over parts of the line to break it up visually. It may take a little futzing with it to get it right. Even if you don't care about the line on this one it is a good technique to learn for when you might really need it. Sometimes a little trompe l'oeil can save a ton of refinish work.

look at it with a black light to see if it is glue. You can get led blacklight flashlights now. Mostly used for finding cat pee.

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http://www.Harvestmoonguitars.com

Michael and Dwight were in a hotel room and turned on a black light, which revealed splotches all over the bedspread.

Michael - "Whoa. What are all those stains?"
Dwight - "Blood, urine or semen."
Michael - "Oh God. I hope it's urine."

Black light flashlight seems like a real handy tool...

It is, and cheap too.

Black locust glows under black light - my latest application.

Thanks for the suggestions. I'm off to try to source a black light flashlight and a fin-tipped brush.

Great suggestion. I mixed 5 ml of sealer with 3 drops of golden brown and gingerly painted it on. Definitely reduces the visual impact

Before:



After:

Yeah that looks a lot better, that is a strange thing.

Does a blacklight work with ALL glue tho? I know LMI formulates there's so that it does.

I seem to remember a previous thread here when a water-based finish made a Titebond joint show up like that. I searched for it but couldn't find it.

I used a water based finish/stain on my new window in the living room 28 years ago. I mixed up some white wood glue, probably Titebond, and sawdust to fill the holes on the trim. The pressure must have been high on their nailer; and and I thought I'd make it perfect. I sanded it smooth, and it looked nice.

You can still see each one, AND the 1/2" circle around them. Luckily I did this before I started making instruments. I like hide glue. Wash everything with hot water.

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Why be normal?

Is there a reason why a water-based sealer or finish would highlight residual glue but solvent based sealers or finishes would not?

I've done this same type of bookmatch type of joint with Titebond on Macassar ebony, Indian rosewood, ziricote, walnut, mahogany, khaya, maple, bubinga, and sipo and used the same sealer as Mark on all of those and haven't seen that happen. None of those were stained though. Makes me think Mark's idea that the poplar absorbed glue that didn't take the stain may be what happened.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

When you work with modern plywoods you have to be careful to not sand them very much. The face veneer is so thin that you reach the area that is impregnated with glue in short order. Even if you still have wood grain in those areas the glue keeps it from taking stain.
A few years back I did a little cabinet job for some friends and tried to source the plywood from Home Depot. It was so bad the face veneer was completely sanded off on one edge. Probably half the sheet would have been unusable after even a light sanding. I had to have a cabinet shop order it in for me.

Thanks for all the interest. I want to say up front that I am really happy with the way the Target finishes flow out when applied in thin coats (thanks to J De Rocher for his application tips).

I was not able to find a black light flashlight in my local area. I think a pet supply store might have one. There are now 9 coats of sealer so it might not reveal anything anyway. But I want to get one and check all future projects before applying any stain or finish.

Part of me wants to sand back the finish and investigate, part of me wants to get out of this rabbit hole.

Because of the location and narrow dimension of the stripe, it is hard not to think it had something to do with glue. This shot from an early stage of construction suggests some glue squeeze out was present in the affected area



But why weren’t other areas similarly affected? Plenty of glue was used elsewhere



My stain tests on spare pieces of poplar with various degrees of sanding, grain raising, dye concentration, application methods, “pre-stain conditioners,” and a few different sealers and top coats, gives me this (possibly incomplete) understanding of poplar and dye stains:

Grain is inconsistent in direction and absorption. It can be super absorbent in localized areas.
The dye stain penetration is not uniform. Sometimes the blotchiness is very overt, as on this test piece:


Sometimes it is more subtle, as on this one:


Penetration/dye effect sometimes looks different from different angles

Sometimes an area looks stained, but really the dye is sitting on the surface.


The water borne finish seems to re-dissolve and partially absorb the dye from the wood, changing the stained appearance. Brush application may exacerbate this.


In the unlikely event that I ever do another stained poplar project, I will try different stains, or try to find a sealer that is not affected by the water borne finish. I have not tried zpoxy yet but possibly it would be suitable.

I use to make a lot of furniture with poplar and I could get it looking much like walnut by using Minwax oil-based stains. They go on much more evenly than dye stains.

You can find them in any auto parts store. They use them with UV dyes to find leaks.

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Jim Womack

"Be thankful we're not getting all the government we're paying for. "
Will Rogers