removing discoloration from pvb 1

[copperzoe]

I have laminated 16 oz copper to a sheet of glass using Saflex pvb and the autoclave process.
I put this substraight through chemical etching using ferric chloride. This process has left the exposed pvb VERY yellow. Any suggestions as to what to use to remove the yellow and not delaminate my copper?
This is an artistic medium and not a manufacturing situation...yet.
Thank you for any ideas.

 

[NickE]

I dont know what PVB is, but I do know that Ferric Chloride creates permanent, horrible yellow stains.

When I was a kid I did some home PCB manufacture, the counter top that I spilt the FeCl onto was still stained 20 odd years later. (When it was removed and replaced.) I tried to clean it uncountable times with all kinds of cleaners, noen had any real effect....

Good luck.

 

[CoryPad]

Polyvinylbutyral is the material used for the inner layer of laminated safety glass used for automotive windshields.

Can you cut/grind the PVB?

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[copperzoe]

I will not be able to cut or grind the PVB.

 

[MintJulep]

I suspect that you will simply need to start over.

Either laminate an oversize piece and cut it to size after etching, or seal the edges before you etch.

 

[berti]

Hi there,
from chemical point of view there is a small chance, if discoloration comes from Fe3+.
Try a reducing chemical like Sodium dithionite. It is sold (at least here in Germany)as "Entfärber" - discolorator - for stained textiles, used like a simple detergent.

But by my experience from making PCB in my electronic times before persulfates came up chance is very small, my fingers kept yelolow for weeks.

Regards Berti