A Question About Flashing Slips

[Polydeuces]

Hey y'all, I've been lurking for awhile but haven't done much posting yet. 

 

I was curious about flashing slips. I have a converted gas kiln (which works very well and I got a lot of really good info from another thread in this forum -- thanks!) and am still relatively new at mixing glazes. (Slowly) Developing practical understanding!

 

I really love the look of flashing slips and would love to incorporate them into my work. Though, being that this kiln was converted from electric and is made up of soft insulating brick, I'm a little concerned that atmospheric firings will flux down the bricks, so I haven't messed with it. The kiln's brick wasn't in the best shape to begin with, but I put some love into it and would rather not be wasteful.

 

So I'm curious if y'all have any ideas about circumventing the notion of atmospheric firings to achieve a flashing effect? Might one spray ash on the surface of the slip? Mix more soda ash into the slip? Make a solution and simply brush it on top? Are any of these methods viable? 

 

I anticipate being advised to use saggars, which I'm not crazy about as the kiln just barely breaks through a "medium class" for top-loaders -- not a whole lot of space. Hopefully can circumvent the use of them, too. Holding my breath over here for a guru's advice!

 

Thanks!

Kevin

[neilestrick]

As you know, flashing slips work best in corrosive environments like wood, salt, and soda firings. All 3 of those are really bad for soft brick. Wood not nearly as much as salt and soda, but still bad. I wouldn't recommend doing any of them in your little converted electric kiln. There are products that people swear by for protecting soft brick from vapor firings like ITC coating, but it's quite expensive and doesn't work on old bricks very well.

 

Your best bet is to pursue glazes that flash without adding vapor to the kiln, like shino glazes. There's a huge world of experimentation that you can do within that type of glaze, and your kiln won't be harmed.

[Polydeuces]

Thanks for the response & practical wisdom, Neil! 

 

If I may pose a question -- would adding combustible material to the slip, or applying it after the slip is dried on the pot, be a terrible idea? Or another way to ask the question -- why would that not work? Would it essentially create the atmosphere that I am attempting to avoid? Just trying to find some clarity on this, as there doesn't seem to be much information out there on the matter.

 

Along that vein, what elements are present in Shino that create the flashing, and is it possible to merge the two to perhaps have some of that effect "cross over?" I'd like to eventually not be a newbie with all this, thanks so much for your time!

 

Best,

Kevin

[Mark C.]

Helmer Kaolin flashes in my salt kiln well-you could try some slips with that .It works well in wood fires as well.

[Magnolia Mud Research]

Spray soda ash (or bakiing soda) on unglazed bisque ware before loading the ware into the kiln. You can get "flashing " on most clay bodies with this technique. Slips can help too. You don't have to have a salt or soda or wood kiln to get the effects.

 

Test test test

vary how much where you spray and where you don't spray

 

LT

[neilestrick]

Adding combustible material to a glaze won't necessarily create flashing, but it will create localized reduction. Typically that's done by adding very fine mesh (800) silicon carbide to the glaze. Too much and you get a bubbly crater glaze. But you're firing with gas, so you don't need to do that since you can just reduce the whole kiln. Adding larger particle combustibles will burn out and leave voids in the clay.

[Polydeuces]

Spray soda ash (or bakiing soda) on unglazed bisque ware before loading the ware into the kiln. You can get "flashing " on most clay bodies with this technique. Slips can help too. You don't have to have a salt or soda or wood kiln to get the effects.

 

Test test test

vary how much where you spray and where you don't spray

 

LT

Thanks so much for this advice! I tried out a handful of pieces with it, and it came out well enough that I'm going to continue experimenting. I just made a fresh batch of 50 test tiles, so I'll be testing a variety of different slips & saturations. And thanks everyone for your contributions!