Jump to content
Sign in to follow this  
Pots by Char

Excessive Crawling On Low Fire Glazes Turns Out To Be A Smashing Success On Refire.

Recommended Posts

recently I have had some excessive crawling of some 04 glazes..places where the glaze crawled off over half of the pot.  I reglazed with a different glaze and refired and these pieces turned out awesome...they look like cone 10 ..lol.. now the question is...can anyone help me discover what caused the crawling in the first place so I can try to recreate these for future use.

Share this post


Link to post
Share on other sites

All glazes were brushed on and the glaze I used the first time was one I made using Gerstley Borate, EPK and Silica. The glaze used on the refire was a commercial glaze from Amaco. All pieces were wiped with a damp sponge. The running water  is outside the studio so rinsing would be a bit problematic as compared to wiping with the damp sponge.  I could if needed bring in a bucket of water and dip the bisque in that to rinse.  I have a small studio with only room for me in there with all the stuff that is in it.  I try my best to keep it clean but it does get a bit dusty from time to time.  Would firing without peeps in the holes have any effect on it?  My son has two large dogs and they can get into the patio where the kiln is set up and they have a habit of pulling out the peeps and destroying them..not sure if they eat them or simply chew them into dust...but I have lost all 3 peeps to them. So I have been firing without them this past month.

Share this post


Link to post
Share on other sites

can anyone help me discover what caused the crawling in the first place so I can try to recreate these for future use.

Harry Frasier, in "Ceramic Faults and Their Remedies", cites several factors that could result in crawling: oil (skin or lotion), grease, dust, or similar deposits on the bisque surface; knocking unfired glaze surfaces - especially those with binders to increase shrinkage/harden surfaces - resulting in a loosening of the glaze from the pot surface; over-quick firing of glazed wares still wet from glazing (more often in once-fired wares); items being packed too closely during firing; etc. Could also be a result of soluble salts in the water used to mix your glaze; uneven application/thicknesses of glaze; uneven thicknesses in wares.

 

It is maddening enough when a fault occurs and we don't know why it happened; still more maddening is trying to intentionally replicate that fault not knowing how it happened and the list of potential causes is large.

 

And, no, the lack of peeps/firing without peeps is not likely contributing to the crawling.

Share this post


Link to post
Share on other sites

You could try adding magnesium carbonate to your base glaze to make it crawl. Line blend of your base plus up to 50% MgCO3, fire that onto your tests then do your second glaze over top. This would be more likely to work than trying to recreate an accident.

Share this post


Link to post
Share on other sites

I did throw some replacement peeps but they ate those too . Thanks for all the great replies.  Going to do a test with the mag carb that sounds real promising.

 

Have you worked with crawl glazes before? If not, there are a couple things you need to do differently with them than regular glazes. Mix them up really thick, they need to show cracks in the glaze prior to firing them. Also, the dry glaze tends to flake off the pot easily when handling them so it's a good idea to apply them then put them in the kiln when still wet. Use a good kiln wash or fire on a waste piece until you get to know them as they sometimes drop bits off during firing.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.