Darryl Keil Last Activity 2024-10-10 3:42 PM
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F Buck

 
Subject : Black Spots on Curly Cherry Veneer
Posted : 2005-01-25 5:32 PM
Post #32013
I used a homebrew flattening agent, water, alcohol, glue and glycerin and applied it to some curly cherry pressed between kraft paper, newspaper and two melamine cauls. I only changed the paper once in 3 hours. Then it was set overnight. In the morning, black spots had randomly appeared in the veneer. I expect that this was some sort of fungus. Is this correct?

Secondly, I have applied this cherry veneer to 17 sides of speakers sucessfully (without using the flattening agent)using Titebond Cold Press Veneer PVA. On the 18th side the black spots appeared with some rather large splotches of stain in one corner of the panel. The only thing that I did differently was the length of time between the cauls. I usually left it for 6 hours but this time it was left for about 18 hours. Was the cause mildew from the water in the glue? Was the panel left too long? Is there anything that can be done to remove the stain?
Attached file : blkchryspts.jpg (11KB - 488 downloads)



 
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Darryl Keil

Posts: 1453

Joined: 2003-05-22
Location: Maine

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Subject : RE: Black Spots on Curly Cherry Veneer
Posted : 2005-01-27 9:57 PM
Post #32016 - In reply to #32013
F Buck,

Well, it seems unlikely that fungus would appear while flattening your veneer in such a short time. My guess is something in the cherry interacted with the flattening solution.

I can only speculate as to the cause. Is it possible your water is very hard? or something got ground into the surface of the cherry that you didnt see?

Stain in veneer is very hard to get out since it usually penetrates so deeply. Sorry I cannot be of more help on this one.

Sincerely
Darryl Keil


 
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Carl Morrell

 
Subject : RE: Black Spots on Curly Cherry Veneer
Posted : 2005-09-26 5:37 PM
Post #32431 - In reply to #32016
I just had this happen. Discovered it today.

Freshly made flattening solution with a new bottle of glycerin and probond glue. Used newsprint with no print on it. 3 hours after I applied the flattener about half my sheets came out terribly spotted. Unusable and at a great cost. Over $100 worth of rare cherry crotch ruined.

Water here is soft, next time maybe distilled water?

Dammit, this hobby can be frustrating.


 
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jerry curry

 
Subject : RE: Black Spots on Curly Cherry Veneer
Posted : 2005-09-27 8:47 AM
Post #32432 - In reply to #32431
Woods that are high in tanic acid (oak, mahogany, cherry etc) will turn black when exposed to water if there is any trace of iron present. Could this be the source of your problem?


 
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Brian Gray

Posts: 339

Joined: 2004-01-21
Location: Sandusky, OH

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Subject : RE: Black Spots on Curly Cherry Veneer
Posted : 2005-09-27 9:00 AM
Post #32433 - In reply to #32432
I have to agree with others that I'd look to your water first.

I always keep some distilled water in the shop for cleaning up yellow glue with a toothbrush.

I'll admit that I've never used distilled water with my flattening solution, but I think that I will from now on. Won't hurt.


 
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Carl Morrell

 
Subject : RE: Black Spots on Curly Cherry Veneer
Posted : 2005-09-27 12:53 PM
Post #32435 - In reply to #32433
The irony of this, is I have distilled water in the shop. Just did not think I needed it.

So if it is an iron/tannin reaction, is there any way to undo this?

Bleach the wood? dye? (ugh and double ugh)


 
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russ garcia

 
Subject : RE: Black Spots on Curly Cherry Veneer
Posted : 2005-09-29 2:26 PM
Post #32439 - In reply to #32435
Black spots happen to me at times. Do this: use a glue that doesn't have water in it. Keep everything very clean. Use heat to set the glue and remove it from the bag as soon as possible ( 1 hour is best).

To get rid of the spots use oxalic acid ( a very mild bleach)-don't forget to dissolve the oxalic acid in distilled water. Most hardware stores carry it.
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