Veneer Layer in Segmented Bowl Turning Grey After Gluing

Hi Greg

Very nice bowl, did the discoloration happen to every piece of glued maple on this bowl ??

I very rarely glue anything other than a waste block, so I wont be much of a help to you, but did this happen before, ever, what was different, I mean wood dryer or not, temperature higher/lower, and are you sure it was not there before, and you only see it now after it is finished ??

Hope someone can shed some light on it, I do know that fungus does discolor a lot of woods not just maple, but I think that is only possible to happen if the wood is wet, not on dry wood.

Have fun and take care Leo Van Der Loo

Looks to me like a case of mis-matched segments.

Walt Conner

If I were to hazard a guess I'd bet that it wasn't the glue, but sanding it that did it. Probably some really fine walnut dust has stained the maple. Next time use purpleheart. If it's light purple instead of grey then you've found the culprit.

Might be a good tack rag could have helped w/that, or maybe some mineral spirits on a cloth...

...Kevin

An inaccurate observation from one who has apparently never seen the refractive nature of soft maple illluminated by a point source lamp.

Sort of like a Disco Ball...

Greg G.

Hi Leo,

Happened only to the veneers, not the remainder of the solid stock maple or walnut. Some of the veneer was glued up into stacks, as shown by this photo:

The spots are clearly visible. This occurred within several hours. It was clamped between clear kitchen plastic wrap and cawls, so no contamination from an external component could have occurred. I discarded this piece and made another. This was then cut into smaller pieces to create the feature ring divisions. It didn't seem to discolor until glued into the feature ring. Time between the veneer glue-up and ring assembly was one day. Total elapsed time for the entire bowl was one week.

Before posting my query, I tried clamping several veneers together with both water and glue. Only the glued pieces discolored. It's a mystery to me. I even considered the rubber roller on the glue bottle applicator as the culprit, but apparently not.

Thanks,

Greg G.

Hello Kevin,

Happened only to the veneers, not the remainder of the solid stock maple or walnut. Some of the veneer was glued up into stacks before assembling into the feature ring, as shown by this photo:

The spots are clearly visible. This occurred within several hours. It was clamped between clear kitchen plastic wrap and cawls, so no contamination from an external component could have occurred. No sanding contamination either. Just glue and veneer. I am beginning to suspect a possible cross reaction between the two species of wood used. One of them is an exotic I am otherwise unfamiliar with. I believe it is called Makore (Pommelle).

I will have to run more tests to determine the exact cause, and what materials are involved. I bought the veneers as an assortment of species. I think I got about 68 sq ft for $25 on special. Perhaps that's why it was on special... ;-)

Incidentally, I always wipe down my projects before finishing, and again, the discoloration began before any sanding or finishing was begun.

It's not a total loss, as it looks good enough to put popcorn in, but the greyed maple veneer lessens the impact of the thin detail lines.

Thanks,

Greg G.

It looks like metal stains to me. I get them on some of my green turned bowls and think that it comes from metal dust from the grinder. If you clamped it with water, then it wouldn't be the metal. Try a little lemon juice or I think boric acid works also to remove metal stains.

Thanks for the input. No, it wouldn't have been metal causing it, due to the fact that it occurred on glued up veneer stacks rather than the completed project. I've got a bunch of test veneer glue-ups drying the in the gar^h^h^h shop as we speak. Maple to maple, maple to walnut, makore to maple, makore to makore. Clean glue and no foreign applicator used. I'll figure it out eventually. All this because of my desire to imbed a reddish detail band - shoulda used black walnut.

I'm thinking that there is something in the makore that is transferred with the glue into the maple, and the combination of glue and exotic salts is discoloring the maple. A water wetted clamp-up between the two species did nothing adverse. We'll see in about an hour...

FWIW,

Greg G.

Let me rephrase that - was half-asleep and sounds kinda snappy...

It isn't the segments that are the problem, they are fine. The apparent mismatch of the segments is actually a reflection aberration caused by the camera flash and this particular board of maple.

The problem is in the detail rings - the tiny little 1/32" bands that circle the bowl above and below the feature rings and in-between the segments of the feature ring. The picture doesn't show this very well, but it was on hand at the time.

FWIW,

Greg G.

I think you're right. I'm finding it difficult to see the problem, but it looks like the upper thin bands should be light surrounded by dark. The 'light' looks muddy. On the foot it looks ok to me.

Hi Greg

Sure looks like fungus to me, are you able to do some glue up without the plastic wrap ?? Doesn't take long for fungus to grow in the right conditioning. I'm probably wrong but it's worth a try maybe.

Have fun and take care Leo Van Der Loo

That makes two votes for reactivation of black mildew.

I've not tried segmenting so I've no idea how workable this would be. Just a thought after seeing a lot of segmented pieces. Would like to hear your thoughts.

TomNie

...

Greg, I suspect a reaction between the glue you used and some treatment the veneer had

Thanks, I'll try not to bother you again.

Walt Conner

Thanks, Tom,

From everything I've been able to glean, some guys apparently use solid bases, some segmented. Those that use segmented bases apparently hollow out the center to a thickness of 1/8" or so, and install a plywood plug underneath - or completely drill out the center and use a solid plug. I like the look of the segmented bases, so I have been opting for the former method. I have solved the problem of matching the center points and such, so I personally don't feel a solid base is an advantage. One person claimed that the perfectly aligned center points visible from the inside "made the looks of it" - for whatever that subjective comment is worth.

In my estimation, the vessel should be more durable as the entire unit breaths and expands/contracts in unison, whereas with a solid base, the upper rings expand in all directions while the base in only one. It seems that using a solid base almost requires the use of a veneer layer between the two to prohibit/retard cracking between the base and the segmented rings. Of course, if the grain orientation of the other rings aren't properly aligned, all bets are off anyway.

That's my theory and I'm sticking to it... ;-)

Of course, all of this is irrelevant to the discolored veneer problem. I have yet to come to a conclusion on that matter. I glued-up a group of test subjects, and wouldn't you know, not one of them exhibited the problem. Argghh... Seems it only demonstrates the discoloration issue when installed into a vessel that has a minimum of 10 hours of time invested...

Just like woman - a complete and utter waste of time...

FWIW,

Greg G.

I didn't make myself clear. The solid part I was referring to was the lower portion of the bowl between the two segmented layers at the top and the segmented bottom.

I think the segmented bottom adds to the attractiveness of the piece. Just a plain center/bottom bowl part seemed like it would add drama. I'm not an arteeest so maybe my thought is goofy.

Now your feelings of disparate movement may still be your answer. I guess you'd have to assemble your segments, then add to a solid blank, then turn and hollow about like normal. Then add to your segmented bottom.

TomNie

Greg,

I know you don't know me from a hole in the wall, but FWIW to you, I think I would go along with the spalting crowd. There's a reason for that, though. The "bullseye" effect in some of the larger "colonies" look just like mold growing in a petri dish and the fact that the smaller discolorations seem to very closely follow the curve of the grain.

It could very well be, especially since this is a veneer, that the blade used to cut it originally, transferred spores to the surface of the piece you have here. Perhaps the chlorine in the water you used to experiment was enough to inhibit the growth of the spores, and the moisture in the glue, coupled with the sealing with plastic wrap, provided the optimum climate for awakening the dormant spores.

Make it three. Those weren't visible in the first photo I saw...

...Kevin