Rein red (cone 6 tin chrome red glaze)
Over the past 3 years or so I've been talking to a glaze fanatic; we will call him Rein. Rein has been slowly egging me to make glazes I dislike. I know, I know, I am a hipster with glazes. He knows I have a hard spot in my heart for tin chrome reds. It’s to such a point that I will buy work with amazing tin chrome red applications. My hated for the glaze wraps all the way back around to admiration. So of course he challenges me to make one I’m satisfied with. Well, here we are. Were making a glaze called Rein red and were doing it the way I wanna do it because it’ll bug him a little. Lets start with the basics.
Tin chrome reds are generally an oxidation fired glaze with chrome oxide and tin oxide. When combined they produce a purple…..pink….burgundy… red….ish color. The range of how dark or light the “red” can be in a tin chrome red is based on the glaze base and amount of tin / chrome . Notice I keep saying “red” with quotes. That’s because this is not red to me whatsoever. I will die on this hill. Tin chrome reds are so difficult to get anywhere near the real color red that I often call it burgundy or dark pink. I am personally very fond of the Tin chrome that clayscapes sells, Clinton pottery red. Mostly because you can lower the specific gravity (ratio of water to mineral) in the glaze to get a white running effect with drops of red. This type of glaze is very sensitive to application, SG , base recipe, and viscosity (which is why I imagine he wanted me to make it). Lets look at my first try.
Rein red test #1
SG: 1.5
Cone: 6 ox
Application: 4 second dip
Clay: Laguna porcelain
Notes: ok…. That was easy. I like it, I like it a lot infact.
Same tile but the back
Notes: I can’t quite figure out of the white is because of the melt “a hotter firing” or if the SG is too high. Generally people aim for a solid color. Of course, I want the versatility of lowering the SG for white/ red but we have to establish a base of color before tuning. At the time of this test I was using 6 tile because EPK go bye bye.
The strange is that this is 0.08% iron chromate (I'm not using regular chrome oxide because it’ll bug him) and 11% tin. I am aware that the chrome has to be very very low. At times my scale has trouble registering anything under 0.06 and below.
Red rein (still test #1)
Sg 1.4
Application : 4 second dip
Clay: porcelain
Cone : 6 ox
A lighter SG with this type of glaze will = more white if you do it right. Compare this glaze to the 1.5 SG with the same application test you can see it easily.
Let’s look a test #2
Rein red test #2
Now here is the strange one
SG: 1.5
Application: 4 second dip
Clay: laguna porcelain
Cone: 6 ox
Notes: the strange thing about this one is that this was 0.5 iron chromate. its damn near purple.
Test #2 was strange, I wanted to see how much chrome I could put in. I assumed 7-8 times the chrome would give me straight purple. I did get a deeper purple but I thought it would be much deeper. From this point on we must be at 0.1 iron chromate and under. Over that is too deep. At this point I started to go….. a little crazy. I went through a rabbit hole of tests that I am not gonna show you because I went a little insane. I decided my first test was good enough and whats more is I made a new glaze by reducing the iron chromate very low low. Take a look.
Mochimon pink
. 9.8% tin 0.07% iron .
Sg: 1.5
application: 5 second dip
cone: 6 ox
clay: laguna porcelain
This was a great surprise. I see lots of potential in this glaze. A little phase separation, Breaking where thin, Love it. It’s right on the cusp here. I think 0.065 would also be fine.
A few things I have learned about tin chrome red glazes. Firstly they seem to require a good amount of tin. I noticed if I used too much tin I would get these white edges I like so much but if I lessened the tin I would mess up the color quite a bit. I could not go under 8% without punishment. On top of that, the chrome is refractory; More then you may think. There is defiantly a balance with tin and chrome but because the tin needs to be high relative to the chrome it’s better to shoot for high-ish tin and around 0.1% chrome per every 100g batch if you are looking for starting amounts. Please keep in mind that these are not UMF molar amounts (which I prefer to work with) these are just the additives that make the color (mostly) without considering the base recipe. The base recipe seems to need high calcium. The alkinline earths can change or mess up the color. CMW teaches that a little magnesium can disrupt the “red” in tin chrome reds turning it more white as you add greater amounts of magnesium. I found this to be true. I tested it a little.
Rein red test #6
Sg: 1.5
clay: porcelain
cone: 6 ox
application: 4 second dip
I added 2.5% talc to this recipe to introduce a little magnesium and look….. the pink it having a hard time coming through.
They were right. The magnesium supplied by the talc is making it harder for the color to come through. In conclusion, this is an easy glaze to make as long as you keep a few tings in mind. Keep the base recipe calcium based. No other alkaline earth needed as it will interrupt the color if too much is added. The balance of tin and chrome are important. It seems to need a good amount of tin relative to the chrome. You can get a very good tin chrome red with 0.1% chrome but the tin needs to be around 10% (assuming your base glaze is good). Im working at cone 6 so of course I have boron in my glaze but that’s a given.
