It all started in highschool... my obsession with pottery, science, and applying the two together. One day my pottery buddy sienna showed me a video on pinterest of a potter altering a pieces copper flash with a blow torch, that had inspired us and later that day i found my friend with my glaze atomizer and no proper safety precautions, filled with a 100% copper carb. (Aq) solution.
She stood on the pavement beside our schools loading dock and sprayed a moon vase she bisqued the other day. Our first problem was transportation, the glaze isn't stable pre-firing any contact will take the glaze off the surface, so handle from the inside, bottom, or other unglazed surfaces.
The second, and really, only other problem is changing the colours. When you heat the piece it will sound like its cracking, pay attention to this when it happens turn off your torch and let it cool naturally return to work for final touch ups. You can do this with anything that produces heat more than 600°f.
I prefer the use of MAPP gas torches because they have a fast heat transfer and gives interesting textures on large surfaces. Other gases work excellently too, butane, propane, and even standard solid fuels work. For the widest bands of colour use a wider flame that engulfs the pot, otherwise try to keep the stresses in the pot even so it does not crack.
REVIEW OF PROCESS:
Recipe:
100% copper carb.
•Mix with water to standard glaze viscosity.
Application:
•agitate frequently to avoid settling of copper carbonate
•spray or brush several coats as thick as desired. In thicknesses over 9 coats (sprayed) or 3 coats brushed have a tendecy to bleed. (haven't tried dipping)
Handling:
•Use gloves
•When spraying use a particle mask appropriate for the particle sizes youre using
•DO NOT TOUCH GLAZED SURFACES! Not only is it poisonous (copper salts are used as pesticides and herbicides,) but your glaze will smudge and youll have to glaze again or deal with it.
Firing:
• ^06-6 ox
•let me know about other firings if you try them. I will update this article when i try this method in ^10 redux.
Post-firing treatment:
• slowly wave a torch over the surface
• or, put it in a fire and hope really hard.
You don't need a raku kiln to replicate all of the raku effects anymore. If you know a potter who loves raku but lives in an urban environment, just send them the link! They'll love you forever.