Using Flux

[Dennis]

Anastasia young is rather ambiguous about how reticulation occurs and talks a bout areas rather than layers. She does however suggest 'seeding' the surface of sterling with scraps of fine silver to shortcut the stages of depletion gilding.

[ps_bond]

She does however suggest 'seeding' the surface of sterling with scraps of fine silver to shortcut the stages of depletion gilding.

As described, it looked to me more like fusing than reticulation.

[art925]

Sorry for the delay Dennis - I've been making sure I got my facts right first!

Depletion gilding/depletion silvering involves oxidising the copper content of the top surface of the silver. Pickling removes the oxide from the top surface. Oxygen can penetrate the alloy when it is at heat; pickle, obviously, can only act on the outer surface. Repeated annealing depletes the copper content further to leave a very thin skin of pure silver once it has been pickled clean. All according to Brepohl.

Here's the bit I still haven't found an adequate reference for, so is my understanding: The sub-surface copper oxide (aka firestain, but deliberate this time!) has a different rate of expansion/cooling than the fine silver, so heating the thin skin of silver (+ some or all of the oxide) to molten results in random movement of the surface as the 2 dissimilar metal/metal compounds cool. What I haven't found yet is whether the movement is purely down to the surface silver, or it is the oxide layer that moves and the silver coats it.

If anyone has a better reference to work to that'd be good - something with photomicrographs better yet!

BTW - the description of reticulation in Anastasia Young's book is wrong.

Hi Peter, I am not an expert but I think I understand why you are unsure; following the pretreatment as you outlined above which provides the pure silver layer, I tend to bring my metal to a temperature where the copper enriched inner layer melts yet I try not to melt the upper pure silver layer so that it remains intact. I do this purely by eye, so the core melts then cools causing the reticulation to occur, I have little patience so I use a hot flame and move it quickly over the surface. The other methods outlined by Oppi Untracht suggest that this process with a lower temp flame moving slowly over the surface of the metal until reticulation occurs can prevent the copper oxide formation internally which will be of benefit if to piece is to be highly polished. Method 3 uses no pre-reticulation ie use silver alloy, heat until reticulation occurs. I think this method melts the uppermost layers and creates the texture. Uppi suggests that this method will not create a pure silver layer, but the post reticulated piece can be depleated.

Sorry I currently have no photos of my process, but when it gets a little quieter I will be happy to help with photos.
Les

[ps_bond]

I should have looked at Ganoksin:

http://www.ganoksin.com/borisat/nena...ticulation.htm Reticulation - Ridges & Ripples by Sharon Elaine Thompson
http://www.ganoksin.com/borisat/nenam/reticul.htm Reticulation Notes by Charles Lewton-Brain 1997
http://www.ganoksin.com/borisat/nenam/firescal.htm Some Thoughts on Fire scale by Charles Lewton-Brain

The point is made in the first article that the MP of fine silver is above the MP of sterling, so it is suggested that it isn't down to sub-surface oxides, merely the difference in the 2 metals.
Then it goes on to say that no-one really knows what is going on in reticulation... Surprising. I wonder if there's a thesis to be had there?