Interesting gilding video showing a dome being gilded.

[erik winkler]

I found a nice video of a dome being gilded.
Interesting points are the steps they made:
1: Ammoinium Citrate, all corrosion products removed.
2: Flexible chalk.
3: Wash primer, resin phosphoric acid, zinc chromate.
4: Zinc chromate resin primer.

I can understand the steps and materials, but what I do not understand is the use of phosphoric acid on copper..........
In my opinion it will disolve the copper....?

http://www.youtube.com/watch?v=5AXVBx0h9Qc

Erik

[Patrick Mackle]

Erik,
As a matter of fact I just cleaned the bottom of a copper clad stainless steel stew pot with years of heat tarnish last night. I used an off the shelf tub and tile cleaner
and it worked fairly well on the copper, but when I added some scrubbing cleanser (Ajax) which contains pumice abrasive,
the two combined together REALLY got the job done nicely. The added pumice removed the copper tarnish mechanically, and revealled
fresh copper for the acid to etch brightly. Neutralized with fresh water rinse.
The biggest problem I feel on this dome was the "DAP" product. I hate to say it but I have never been happy with some of their chalking
products. In my applications in remodeling my house, I found that they shrink and fail quite badly, and those were INDOOR applications on NEW materials.
I can't imagine using them in outdoor elements.
Pat

[erik winkler]

Pat,

But why would they use phosphoric acid on copper after the wash primer?
I think they would remove all primers with that acid and make the washing primer unnecesary.
Or is the washing primer an remover also?
It sounds all very scientifically and art restoration/presevation well thought through...
It is funny that you allways have your own smart thinking solutions to the problems and work just as fine.
Erik

[Patrick Mackle]

Erik,
Actually I did not think that the overlaid text notes on that video were very accurate, or planned in such a way as to be a step by step do it yourself.
Especially the overlay that mentioned the resin, chromate and acid all at the same time. Obviously they would not be combined together. The first line seemed like a heading to me.
I found it confusing, whether it was intentional or just an oversight. And the fact that they used "DAP" uugghhhh.... Definitely not time tested in my opinion.
Pat

[Kent Smith]

I agree with Pat about the DAP. With Copper I would solder or use a paintable putty. We used to use a white lead paste to fill.

I would also use a paint remover to remove all the old size and primer then sand, then acid wash, well flushed with water.

I am always interested in how good a mediocre gilding job looks from the ground.

Good video on the process though.