Crazing Problems

by Shona Cameron

Hi Steve,
I have crazing of my glaze a couple of weeks after firing.

I am using a white earthenware clay which has good plasticitity-fires between 1060-1160deg C. The glaze is a transparent leadless glaze firing between 1020-1080deg C.

I have been bisque firing at 1065deg and glaze firing at 1050deg. At the moment I am re-firing the glaze to 1065deg but if this doesn't work should i try adding silica to the glaze? I feel quite despondent about it all even though I know that's a negative unhelpful attitude!!

Thanks a lot,

Steve's Reply:
First, I'm sorry to hear about your craze frustrations. I can relate all to well. I've had a lot of struggles with glazes and clays not "fitting" together. In fact, you may have noticed that most of my information on the site is geared toward forming clay and then using commercially prepared glazes.

The reason for this is that glaze formulation is very scientific and I'm more of a free spirit, -read as I hate math:). I've tried it, and it just wasn't my thing.

That being said, if you are formulating your own glaze, it is a matter of going back to the drawing board and testing, testing, testing. By the way, if you are formulating your own glazes, I commend you, just keep your scientist hat on and remember that it takes patience and testing. You truly are creating.

On the other hand, if you are buying clay and glazes, check with the manufacturer to make sure that the recommended CONE temperature is compatible in both.

You referred to your FIRING temperature, but that isn't really a great measure of the "heat work", which is temperature PLUS time, that is being applied to the ware. CONES will give you a more accurate measure of heat work and therefore a more accurate measure of how compatible clay and glaze truly are.

Also, here is a great article that says all of this much better than I have. Plus, it addresses your mention of adding silica. Check it out.


Click here to post comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Pottery Frustrations?.

Where to Next?

Learn How This Website Got Started

Watch Pottery Throwing Videos

Share Your Photos

Add YOUR 2 Cents

Share this page:
Enjoy this page? Please pay it forward. Here's how...

Would you prefer to share this page with others by linking to it?

  1. Click on the HTML link code below.
  2. Copy and paste it, adding a note of your own, into your blog, a Web page, forums, a blog comment, your Facebook account, or anywhere that someone would find this page valuable.

Feeling Frustrated?

My bestselling Kindle e-book The Despicable Five solves the 5 most infuriating problems every beginning potter faces.