Friday, July 29, 2011

Modifying metal surfaces

The last part of this chapter looked at real metal surfaces eg. copper, brass, aluminium and how to manipulate them by eg. application of heat, embossing, punching, chemical tansformation.

I looked at a number of foils, cans, tubes etc and purchased a few metal shims and meshes to examine.
Holding the shims in a gas flame or under a heat gun produced lovely colour patterns.

I embossed a few using a Cuttlebug intended for scrapbooking purposes but works beautifully here with copper mesh and also in 9.12.


What I was more interested in however was changing the surfaces of these metals chemically so in true experimental fashion (as is my training of course) I set up jars with strips of copper, brass and aluminium/brass shim and added various substances to them to see how the metals reacted over time.


9.13 shows the 3 strips removed for photographing after 30 mins in a shallow level of vinegar.  You can see where the liquid level has been from the patination on the brass strip.

5 different liquids were used:
  • vinegar
  • Easy off Bam (corrosive floor cleaner)
  • Sigolin (a Brasso like metal cleaner)
  • mixure of ferrous sulphate in vinegar
  • mixture of alum in vinegar
and the strips were photographed after 30mins, 2 days and 1 week in lidded jars at room temp.

I found that the brass strips were most easily discoloured and chemically attacked, very little happened to the surface of the copper (oddly enough) or aluminium. I know that normally copper would certainly be discoloured so not sure what was happening here. Anyway, as far as the brass was concerned,  keeping the strips in the air above the liquid had most effect.  Below the liquid level simply eroded the strips away with time if anything was going to happen.
I won't bore you with all the photos but a few are below.

9.14 Easy off Bam after 2 days

9.15 Sigolin after 2 days
9.16 Easy off Bam after 1 week (aluminium disintegrates)
Clearly to use these in textiles you would not take the patination to this extent but you can get interesting shadings - I particularly like the effects on brass I found.

I plan to examine commercial products eg. liver of sulphur, for discolouring copper and brass a little more as I'd like to control the colours achieved and maybe use sections later in my 2nd assessment piece.

No comments: