Creating Lava Glaze: Cone 10 at 5?

[Ben xyz]

Had read somewhere that a cone 10 glaze can be fired at cone 5 with the addition of Silicon Carbide (around 7%) in order to create a lava-type glaze. I’ll start with Chun Blue; also a Reitz Green one. Thoughts? Have had success with Marilee’s Lava recipe in the past with added Copper at cone 5. Thanks!

[neilestrick]

I think it depends on the glaze, and whether or not it is melting enough at cone 5. Why not just do it with a cone 5 glaze? It works with the silicon carbide, too. 7% is likely overkill. I've had glaze lava with less than 1/2 of 1%.

[Ben xyz]

Thanks Neilestrick. I’m guessing the rational is that cone 10 glazes will not be able to reach an adequate melting point at 5, thus preventing them to smooth out. Just a guess - will need to locate the original source about this. Appreciate the correction in my math - the Marilee recipe was asking for 3.4 (not 7). Sounds like I could go even lower. Will now experiment with cone 6 glazes as well.  I’ve been enjoying looking at the ugly beauty of Fat Lava pottery coming out of West Germany during the 60’s and 70’s. Had nabbed a nice catalog from Mark Hill about this movement.

[PeterH]

5 hours ago, Ben xyz said:

Appreciate the correction in my math - the Marilee recipe was asking for 3.4 (not 7).

6 hours ago, neilestrick said:

I've had glaze lava with less than 1/2 of 1%.

 

I think that there is some confusion/disagreement on the amount of SiC in Marilee’s Lava, possibly due to a historic typo.

Glazy gives +0.34 https://glazy.org/recipes/24043

While this paper gives +3.5 https://www.thestudiomanager.com/posts/tag/lava+glaze
Many recipes list the silicon carbide in this glaze as 0.34, but I’ve seen enough others arguing that was originally a typo many years ago, so I went with the 3.5% recipe.

[Ben xyz]

Thanks Peter - I caught that as well. Since prior lava glazes I was using were too often brittle and fragile, I was glad to find Marilee’s formula at 3.5 Silicon Carbide worked well for me, along with the addition of 3% copper for color at cone 6 (shown). Currently awaiting Akiko’s Crater test results at cone 10 (2%  Silicon Carbide).