Bismuth Part 3 (A closer look)
I have recently bought a very cheap microscope; Just to play with. Of course the first thing I did is put some of my test tiles underneath it to see if I could identify anything in the glaze. For example, Make a glaze on a tile, add something to it ( In this case bismuth) and see if you can identify it just by looking at it. Turns out you can. Here is a picture of one of my red glazes without and with bismuth.
Red Materia
Sg 1.35
cone 6 oxidation
4 second dip
This is normal red lotus at cone 6 ox. Notice the MICRO crystals. Yes, I said micro. This goes along with my theory that Kaki red cone 6 ox glazes are really just crystal glazes.
p.s : I am not good at keeping track of the magnification yet.
Red materia
cone 5.5
big kiln 4 layers
burshed
sg 1.4
You can see it right? The crystal formation has changed and you can see little gold dust now. Same glaze, just added one material.
Seems great, right? It’s not all rainbows and sunshine. There seems…..SEEMS! to be a limit to how much you can use. I have tested this a few times and so far it seems too much bismuth messes with the clay or the way the glaze works in suhc a way that it causes bubbles / pitting.
Red materia cone 6 ox on IMCO porcelain.
Pic 1: Looks fine. Not perfect but fine. Let’s look at another pic.
Red materia cone 6 ox on IMCO porcelain.
Pic 2: Big pit. Im not even sure this is pitting. Bubbling maybe?
Red materia cone 6 ox on IMCO porcelain.
Pic 3: more bubbles
Red materia cone 6 ox on IMCO porcelain.
Pic 4: Inside bubbles
From my testing it seems like there is either a limit to how much bismuth can be used in a glaze or….. you cant put it on the inside and outside of a pot because of something to do with absorption with bismuth glazes. I’m leaning towards the ladder. I will be testing to see if I can put a glaze inside of a cup, let it dry for a few days, then glaze the outside just to see if it’s some type of “clogging”; but that’s a later test.
So I did the only thing a ration person would do… I broke it so I could look under the cheap microscope.
Dont gasp at me like that. How ells do you think we were going to fit it under the microscope?
Red materia cone 6 ox on IMCO porcelain.
These twp sherds are the two we will be looking at today.
Red materia cone 6 ox on IMCO porcelain.
Close up of the bubbling
Note: the reason you see the middle clear and the pots’ edges blurry is because the pot it curved. Not a flat tile.
Red materia cone 6 ox on IMCO porcelain.
close up of the small sherd
Red materia cone 6 ox on IMCO porcelain.
Close up of the bottom of the cup.
All very interesting. Two thing I think at the moment with bismuth.
#1: works well with crystal glazes in small amounts, that is, low silica and alumina glazes.
#2: Something is up with the absorption of the glaze into the clay pours. I notice the bubbling problem only happens when I put the glaze on the inside and outside of a pot. I will be testing this by seeing it i can glaze the inside and outside of a pit on different days (letting the pours dry) or by lessening the amount of bismuth. The bubbling seems to be a reoccurring problem with bismuth. Note that the bubbles look almost nothing like pitting, these look different. I have seen crawling, what people call pitting, ECT; This looks like something different.
