001050 Underglaze, White, 16OZ

Here’s a short, personalized review you can use: ⸻ I’ve been using the Speedball White Underglaze on my pottery pieces, and it’s been a great addition to my studio. Once I gave it a good stir and thinned it slightly, it brushed on beautifully—smooth and opaque in just two to three coats. I love using it for sgraffito and surface designs where I want crisp, clean lines, and it fires to a nice bright white under clear glaze. It holds up well through bisque and glaze firings, even at Cone 6. Definitely a solid staple for any potter looking to add reliable white detailing to their work. The only concern that I feel obligated to state about this product is that if you’re going to apply a clear glaze over it, you definitely should be using Speedball clear because it does not seem to like when I use another brand’s clear over it and will occasionally bubble or crack if I don’t use the Speed ball clear.. I called Speedball to ask them about this problem and they confirmed that this is a known issue.

I like that the bottle is the same width top to bottom, this allows even a wide brush to be dipped into the bottle easily. I use 3 coats at cone 6. The result is opaque, pure white without tints of other colors. Additionally, this white can be used in 2 or 3 coats beneath other glazes to give clean, bright results. White, red and brown clays can make glazes appear dull or "muddy", if you use this white in a couple of coats at greenware (recommended) or bisque, it's as if the glaze you apply over this underglaze has been applied to a porcelain type clay. You can use it alone or beneath other underglazes, other opaque or translucent glazes including clear. I've used this white to cone 10. If used alone to cone 10, be sure you have 3 full coats, allowing each coat to dry before applying another and if you're firing higher than cone 6, maybe add a 4th coat to be safe that you have good coverage. I've had this brown slightly in high fire, atmospheric firings such as wood fire, soda fire and salt fire. Hope helpful!

So far, this glaze has done fabulous even at cone 10! The color is bright and not burnt. I would rebuy this brand. The photo shows the red (heart) after a cone 10 firing on a porcelain mix.

***UPDATE*** I reached out to Speedball directly and they immediately sent me out a replacement that was perfect right out of the bottle (4th pic). Was it a pain to have to go through that to get a quality product? Yes, but the customer service was stellar and in the end I got what I paid for so it was worth it. I will purchase in the future with confidence knowing that they will make it right should I receive another bad batch. Original Review: I’m new to speedball underglazes so I don’t know if this is a reflection of their quality or the quality of the seller who sold this particular bottle but the underglaze I received was almost solidified when I opened it. I’ve been doing ceramics for 15 years so I just figured it needed some reconstituting but no matter how many times I power whisked it, the lumps would not dissipate. It went from the consistency of 2 day old oatmeal to the consistency of watery ricotta cheese. I ended up having to run it through a sieve twice and even that did not get rid of all the little globs. Application was terrible, all of the little lumps got worse with each coat. Sorely disappointed- shouldn’t have to work so hard to try to make something usable right out of the bottle only for it to still fail. Worth the extra money to go back to Coyote underglazes apparently.

Works as expected.

This underglaze paints on perfectly and it does turn super black in the bisque firing, however 50% of the time it turns navy blue with a clear glaze on top. I've tried 10 different clear glazes over top and its truly just hit or miss on whether or not it makes it through. Probably wouldn't purchase again but if you are looking to just cone 6 fire without glaze it works great!

So the color is absolutely beautiful which is why I spent so much time trying to make this work for me. Im not sure if I was sent a very old bottle or this is just how these underglazes are by nature but it was extremely gritty/chalky which makes even or detailed application almost impossible. I’ve mixed it, sieved it, and tried adding gum solution, which helped slightly but not enough. When fired the resulting color is a beautiful golden yellow, nicely saturated like amaco velvets. The color is one I haven’t found in either Mayco fundamentals or amaco velvets but the consistency makes application so challenging I think it would be easier to make my own underglaze at this point. Don’t buy or you’ll be tempted to use and then spend hours wiping it off your pot cursing speedball for this crappy product…

I have been looking for a black underglaze that didn't run under clear for years. This did not run! I'm very happy about the results. The bottle says to fire to at least cone 05, but I fired this to cone 06 with a 10 minute hold. Hopefully this helps another potter.

Excelente producto, vino bien empaquetado y cumple con mis expectativas

The best deep black underglaze. Other brand underglazes come out dark gray and speedball is the perfect dark black

We use this in our community pottery community studio. It helps if you water it down as it’s quite thick. But it looks great and we never have any issues with speedball underglazes.

Needs 3 to 4 coats to be opaque

It works, but need many layers