Homebrew PCBs

Tim,
I believe you may be correct regarding "peroxide" as this website amongst many; 

http://microadvances.com/chemicals1.htm

states acrylics have a limited resistance to Hydrogen Peroxide at 28% concentration, and full resistant to a concentration of 3%, I am sure with prolonged exposure to lower concentrations in a CuCl mix, the degradation effect would be the same. Ferric Chloride on the other hand presents no such problems as far as I can see.


--- In Homebrew_PCBs@yahoogroups.com, "Tim Gibbs" <timgibbs@...> wrote:
>
> Hi All,
> 
> A possible explanation for the acrylic crazing is a combination of using
> H2O2 and heat. 
> 
> Benzyl peroxide is used as a initiator for the setting reaction in dental
> acrylic used in dentures.
> 
> Dentures are made using a lost wax casting processes where the denture is
> waxed up and then invested in plaster. The mold is warmed up and the wax is
> removed. A mixture on partly processed acrylic as a fine powder is mixed
> with liquid monomer to form a dough usually with benzyl peroxide as the
> initiator. A little heat is applied and the dough polymerises to form the
> acrylic.
> 
> Patients are advised not use bleach on their dentures.
> 
>  
> 
> Cheers
> 
> Tim
> 
> 
> Is it a problem with peroxide then?
> 
> 'Cause I had a commercial acrylic bubble
> tank that was used for years without problem.
> Then after switching to CuCl (regenerated
> with 40 weight H2O2) it crazed and went
> brittle in about 6 months.
> 
> 
> 
> 
> 
> [Non-text portions of this message have been removed]
>