Porcelaine onefire bisque firing

[Nicky S]

Hi ....... Fired two batches of porcelain ware .The one was “ onefire “ And the other  “bisque» My problem is they got mixed together. Now I cannot tell the difference as I want to glaze the bisque ware .Is there a way of testing the difference

Thank you Nicky

[Mark C.]

I'm a bit fuzzy once fire porcelain clay (never heard of it) and regular porcelain.

I assume you bisques it both right? so it does not matter for a glaze fire which it is.

more details would help about the onefire clay?Is this mid range or high fire clay?

bisquing will not hurt any clay

[Nicky S]

@Mark C. Yes one high fire with porcelain clay  (sorry don’t remember exact temp prob 1240degs  I didn’t  want to glaze that particular batch .When firing porcelain bisque I fire up too 940 degs and glaze to 1240 degs I don’t use cones 

[Mark C.]

Are you talking celsius I assume so. Bisque temp is usually the same for most clays 

I do not bisque with cones either about 1800 degrees F.

Telling apart clays is hard at any state-Bisque state is no exception . I know of no way to tell them apart other than color but porcelain will be white now matter what.

[neilestrick]

So they were both bisque fired, correct? It'll be near impossible to tell them apart. Your best bet is to bisque something of each clay (label them so you know which is which), and compare them. But I bet you won't see any difference if they're both porcelain. In the future, if you're not going to glaze something, go ahead and just fire it up to peak temp without bisque firing.

[PeterH]

@Nicky S >Yes one high fire with porcelain clay  (sorry don’t remember exact temp prob 1240degs  I didn’t  want to glaze that particular batch .When firing porcelain bisque I fire up too 940 degs and glaze to 1240 degs I don’t use cones 

If that's 1240°C it doesn't sound like a bisque temperature. Did you have have two firings with the same porcelain body -- one single-fired to maturity, the other bisque fired?
If so then surely the bisque is still absorbent and the fired-to-maturity is vitrified?

PS What is the name of the body/bodies you are using?

[Mark C.]

Peter is on it-Yes you can do an absorption test-that will separate them as the mature body will absorb less-you can dry weight them and saturate a given time period and weigh them figure out the % in weights-real pain in the neck stuff but its about the only way now.

Peter got the prize of the day-my old brain missed it.

[Min]

If one is fired to 940C / 1720F and the other to 1240C / 2260F and the clay matures at the latter temperature just touch your tongue to the pieces. It will lightly stick to the bisqued pieces and not to the mature ones.

[LinR]

I'm with Min on the tongue test.  Rather like licking the iron railing in winter but not so painful.  Lin

[Mark C.]

OH the tougue test another old brain thought long gone.Great Idea.Its been a long time since I licked my work it always seems to lick me first.

[Nicky S]

4 hours ago, Min said:

If one is fired to 940C / 1720F and the other to 1240C / 2260F and the clay matures at the latter temperature just touch your tongue to the pieces. It will lightly stick to the bisqued pieces and not to the mature ones.

@Min ....... Thank you Just did the tongue test Worked perfectly :-)

[Nicky S]

22 minutes ago, Mark C. said:

OH the tougue test another old brain thought long gone.Great Idea.Its been a long time since I licked my work it always seems to lick me first.

@Mark C. Mark thank you so much for your time and input Just tried the tongue touch and seemed to work :-) But will bare in mind your advice too :-)

[Nicky S]

6 hours ago, PeterH said:

@Nicky S >Yes one high fire with porcelain clay  (sorry don’t remember exact temp prob 1240degs  I didn’t  want to glaze that particular batch .When firing porcelain bisque I fire up too 940 degs and glaze to 1240 degs I don’t use cones 

If that's 1240°C it doesn't sound like a bisque temperature. Did you have have two firings with the same porcelain body -- one single-fired to maturity, the other bisque fired?
If so then surely the bisque is still absorbent and the fired-to-maturity is vitrified?

PS What is the name of the body/bodies you are using?

@PeterH Min came up with the idea of tongue  test ....... Therefore you input was right as too “one fired “is vitrified  Use Audrey Blackman porcelain Thank you for your input :-)

[Sorcery]

You'se didn't get the memo?

CDC said no more licking!

Lol!

 

Sorce