Maxwell

Hey Folks, I'll add a bit more info. I have used several clays including a stoneware white, Salt body and Laguna's Raku K. The salt body I mix myself and the other 2 purchased. Glazes were sprayed, dipped and brushed. Dried overnight before test firing. Bisque to cone 06 which seems quite porous. I use what I think is real Gerstley B from Continental Clay in Denver. The glazes formulas I attached start separating off at about 800F and some does fall to the shelf guard. These little 2# round pots then look like a paper wasp nest, but with large cracks running throughout. 80-90 % of the glaze will sit back down, flux and adhere with a mature appearance at cone 06, but with lumps and thin shallow areas. At this point, I will probably continue to dip or spray, dry well and try approaching the glaze formulas as the problem. It seems that the borax, bone ash and soda ash are somehow involved and not adhering well. Adding more clay will likely be my next step. Tx

Hello and thanks folks for getting involved. I am new to Ceramics Monthly and am not aware of all previous publications, so I am adding additional info to clarify the topic. I am talking about western Raku and I realize you all know the temp range (1470-1830F Cone 06 range) and that Cone 6 is 2232F which is stoneware high fire and my historical wheel house. I am sharing copies of the lead pages from the Ceramics Monthly regarding 15 tried and true raku glazes and the lead page from Gary Fergusons 3 part freebie series on raku glaze formulas. There are 2 photos of glaze tests I did(I usually use small pots as I want to see the effects on shape. All were fired to cone 06 and all fluxed nicely when the residual glaze settled back on the pots. The single pot photo hopefully shows the irregularity on the surface where glaze has fallen off before completion of the firing. These were all cone 06 or less glazes. In fact, the crackles which worked well matured as low as cone 010. My difficulty is really with trying to get the glaze to adhere during the temperature rise. Problem ingredients seem to be frits, borax, soda ash and bone ash. I tried adding different clays to the formulas without suggest, but never more than 5%. Maybe the solution is just adding more clay to the formulas, but why not state this in the formula from the get go. Anyhow, take a look and see what you think. Thanks!! Raku pdf version 3.pdf

Hey Neilestrick, Thanks for the gum info and technique. I have some gum and will give it the next test. Easy since I'm doing small test batches. I did use all of these glazes both dipped and sprayed, but could not get them to stick to the bisque ware during firing. The glaze literally peels half way off at about 800-1,000 F. Do you or anyone have a similar experience or work around that is effective. I've tested the addition of bentonite, ball clay and kaolin without any success. Thanks Again

Hello, I am looking for advice regarding raku glazes that separate or fall off of a ceramic piece during firing. I have extensive experience with high fire stoneware in glaze and salt firings. My raku experience is limited to work I did 50 years ago with crackle glazes and primitive firing techniques. I make all of my own glazes and recently have experimented with raku glaze formulas published by Gary Ferguson and a Ceramic Arts Daily publication of 15 tried and true glaze recipes. Maybe someone out there is aware of these. Recipes containing bone ash, soda ash, borax and ferro frits do not brush on particularly well and then are separating from the bisque ware during firing. I have experimented with different clays, glaze thickness and clay additives without much success. When fired to temperature, the glaze remaining on the pieces is otherwise quite nice. I am anew subscriber and this is my first use of the forum. Any thoughts?