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Would anyone have any suggestions as to what point (in metal thickness) it is unnecessary to apply a counter enamel on silver, simply because the glass cannot overcome the mechanical strength of the substrat?
I realize there would be a lot of factors involved, but are there any "RULE OF THUMB" guidelines?
Bruce
The main rule is-How thick is the metal the same thickness is maximum for enamel. Georgian enamellers use counter enamel that is after final enamelling scraped off and the back of the piece is polished. I never used this but it probably work better than risking cracking because of the stress of the glass/metal.
Rudolf
According to Thompson Enamel Workbook - It is not always necessary to counter enamel. The purpose of counter enamel is to reduce stress exerted on the enamel by the metal after the piece is cool or during cooling. Coating both sides of the metal distributes the stress equally to both sides of the metal, preventing the warpage which normally occurs as a piece coated on one side cools to room temperature. Ideally, both sides of the metal shold be coated prior to the first fire. Once a piece is warped, enameling the other side will not straighten the piece.
In Saw and Solder Champlevé - two pieces are soldered together - 18g. back sheet and 22g. sterling silver top sheet - No counter enamel is necessary because of the thickness of the metals -
I also have a collection of enameled pins and bangles in silver that have very fine layers of enamel on the silver design and no counter enamel - Mostly India and Thailand.
When working with tiles, and bowls, a lot of enamel is placed on the metal and therefore both sides should be enameled for balance. Also one must take into consideration how many times the piece is going to be fired and how many layers of enamel will be applied.
According to Thompson Enamel Workbook - It is not always necessary to counter enamel. The purpose of counter enamel is to reduce stress exerted on the enamel by the metal after the piece is cool or during cooling. Coating both sides of the metal distributes the stress equally to both sides of the metal, preventing the warpage which normally occurs as a piece coated on one side cools to room temperature. Ideally, both sides of the metal shold be coated prior to the first fire. Once a piece is warped, enameling the other side will not straighten the piece.
In Saw and Solder Champlevé - two pieces are soldered together - 18g. back sheet and 22g. sterling silver top sheet - No counter enamel is necessary because of the thickness of the metals -
I also have a collection of enameled pins and bangles in silver that have very fine layers of enamel on the silver design and no counter enamel - Mostly India and Thailand.
When working with tiles, and bowls, a lot of enamel is placed on the metal and therefore both sides should be enameled for balance. Also one must take into consideration how many times the piece is going to be fired and how many layers of enamel will be applied.
Thanks Trish and Rudolf for your help.
I look forward to all replies, and any input is always appreciated
Cheers
Bruce
You always have to use counter enamel. I start with my ground coat, then a base black. The counter keeps the project from warping, and the impurieties inside the steel. The enamel and steel cool at different rates. This inconsistencey in cooling will caust the metal to cool in one direction, and the enamel to cool ing another. If the enamel hasn't been applied correctly, the enamel will go flying, (PING) in all directions.