Nice work...verdigris is produced by treating copper with acetic acid, neutralizing the acidic balance may alter the color...but she could try baking soda and see what happens...or perhaps go to some sort of paint...Copper Sulfate I think can be toxic and I would not recommend it for casual use....

Here is some good reference and materials info...

http://basiccopper.com/wowicoinarcr.html

http://copperhand.com/

Thanks.... she has turned this into a thriving little business, regularly supplying about 70 galleries across the UK together with worldwide online orders ( have a look at the website www.beastiebrooches.co.uk ).

Have had a look at the links, unfortunately these guys don't give much away. Will try to find out exactly what chemical she is using ( think she gets it from the US ), will also try the baking soda idea as this would be fairly quick and simple.

Will keep you posted

Some experimentation may be in order. If this works, it would save her money, and I believe the process would be halted with a simple water rinse.

http://www.mailleartisans.org/articles/articledisplay.php?oldkey=3753

Very nice!

The color in the picture does look like copper sulfate pentahydrate. Unfortunately, this can lose water of hydration, which also causes it lose the brilliant blue color. If the finished piece gradually turns greyer or a greenish color that is likely the problem. This could happen if it is kept in a very dry environment as the varnish only slows down the equilibrium of dehydration. Another possibility may be that other chemicals in the verdigris compete with the CSP or react with the base copper over time (especially if the solution is acidic) in which case a soda ash wash would help.

If you could say what the actual change(s) is & how long it typically takes that would give us a better idea.

Thanks....can only go on what my wife has told me ( never seen it myself yet ).

She says the verdigris appears thicker and paler in colour, this has shown up on some pieces which are about 6 months old. It does not seem to be a great problem as no-one has complained as yet.

I think you are probably on the right track about the CSP. Maybe like the others have said, a wash with water or baking soda solution may stop this happening.

Will find out tonight what the chemical is ( or at least the brand name ).

http://libellulajewelry.blogspot.com/2012/06/etched-copper-with-blue-patina.html

Thanks to everyone so far.

Here's some more info, its manufactured by Mayco as part of their Magic Metallics range, product code MM 305 Rapid Rust.

Have found some application notes, it says non-toxic and can be sealed with MM 502 Matte Sealer

www.maycocolors.com

Probably the best idea would be to use the proper sealer if available in the UK.

Vinegar will do same thing and is easy to handle