Jump to content

High Bridge Pottery

Member Since 19 Feb 2013
Online Last Active Today, 09:13 PM

Topics I've Started

Can A Glaze With A Higher Coe Have Less Crazing Than A Lower Coe?

26 November 2014 - 01:23 PM

Working on a new glaze and I decided to look at their COE's as I had slight crazing. First I put in the one that had the least crazing.


Cornish Stone - 50

Whiting - 50

COE = 848

This recipe has the least crazing.


Cornish Stone - 45

Whiting - 45

China Clay - 10

COE - 769

This recipe had the middle amount of crazing, only small but still there.


Cornish Stone - 40

Whiting - 40

China Clay - 20

COE - 691

This has the most crazing.


So I thought that must be right, so to check I put in a glaze I have that I know doesn't craze. That came out to be 400ish. Can't remember the exact figure as I didn't right it down. Tested another glaze I know doesn't crazy with my clay. Same thing, around 400ish.


Why is the first glaze test with the highest COE got the least crazing  :unsure:


To my knowledge you want a glaze with a slightly higher COE than your clay to have slight compression in the glaze. Too high and it crazes, to low and it shivers.

Correct me if I have F'd up somewhere.

I don't know the COE of the clay.

Three Part Mould Making :(

21 November 2014 - 08:09 AM

Can anybody recommend a good book/tutorial/anything that I can read? Made a few one part moulds and two part moulds with some success so I thought lets try a three part mould. Lots of things went wrong, for one I don't think the soap I used was that good as I came to open the two parts today and it was fused shut  :blink: Also failed at estimating the plaster I needed and ended up with too little for one half.


Here is my attempt 


Attached File  mouldFail.jpg   168KB   2 downloads

How Much Do You Stay Within Glaze Limits?

21 November 2014 - 07:35 AM

I have been doing a few melt tests and one came out that I liked the look of (see picture) It was a test of 1g of Cornish Stone and 1g of Whiting. 


I put that into a piece of glaze software then added extra feldspar/china clay/quartz to bring the glaze into the limit formulas. After that I ended up with three transparent glazes which lost all that I was looking for. I guess the limits are good when you want a nice transparent glaze.


How much do you stay within glaze limit formulas?


Attached File  glazeTest9.jpg   391.83KB   5 downloads

The Double Dip

12 November 2014 - 11:16 AM

I had never seen anything like this technique, after trying it out on a few pots I love it. Firing is on now so the final verdict will be found out tomorrow but it really speeds up my glazing. 


Thought I would share to educate anybody else who has missed out. 




22 October 2014 - 06:04 PM

Well it made me laugh  ^_^ Now it's your turn.


Attached File  ceramicsmeme.jpg   20.08KB   1 downloads