just a little help with my agateware (shrinkage rate/green scrubby)
Posted 20 March 2012 - 09:53 PM
1. for the most part, the pieces i've been making have been comprised of one type of porcelain only (different colors achieved with mason stains). but recently i threw a piece that was made with both amaco porcelain no.65 and laguna dave's porcelain wedged (but not blended) together. the shrinkage rates are 12% for one and 13% for the other. i plan to fire the piece regardless, but i just wanted to ask if anyone knows what kind of chances the piece has of making it through the firing safely. if it was to crack, would it be more likely to in the bisque(^04) or glaze(^6) firing.
2. i always use a metal rib to try to clear off as much of the slip that covers the marbled patterns as i can. inevitably they still need some cleanup once they reach bone-dryness. i use those "green scrubby" scouring pads to do this but it is tedious work and i don't really enjoy it. at my old high school there was a jar filled mostly with normal scouring pads but one of them that i found was a much more sturdy, coarser brand. it worked very well for what im doing because it shortened the length of time spent sanding pieces and didn't trap hardly any clay dust! unfortunately, i haven't been able to find these in any stores. if anyone knows where to find these coarse scouring pads, or has had and overcome this problem with other methods i would really appreciate any advice.
Posted 20 March 2012 - 10:18 PM
I have some questions .
I did not know that Laguna made it in cone 6?so for this I'll assume cone 10 or its an eastern Laguna mix at cone ^6
If you are firing a cone to 10 body to cone 6 the shrinkage will not be 12%
I know nothing of No 65 but looked it up as a cone 5 body with cone 6 as maximum. If they are wedged as one they will be one body which is an experiment till fired
I think it will be fine but under vitrified as you have a cone 10 mixed in with a 5
As far as cracking it can happen in either fire with more chances in the glaze I'm guessing as the body's are so different-and this is just a guess.
In ceramics testing is always a key element and you have a good test going-let us know the outcome.
I'm curious as to why you choose a cone 10 clay to mix in??
As far as the pads if they were the brown or green course ones they sell them at ceramic supply houses. Check the usual online ceramic stores as well
Posted 21 March 2012 - 09:07 AM
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Posted 22 March 2012 - 10:30 PM
mark, you are correct, it is cone 10. for some reason, i didn't pay much attention to the firing temp since it's not below the cone 6 temperature that i currently have available to me. i had apparently been misfiring the dave's porcelain before (with no immediately apparent issues) on its own at cone 6. the two bodies were not wedged completely but left "somewhat separate" within the ball of clay to achieve a marbled pattern. my choice was not based on firing but on color actually. most of my pieces feature a brightly colored clay and the clean white of the uncolored clay body. while i enjoy this contrast, im trying to make my work more marketable. the variation between bright pure white and a yellowish off white seemed more subtle and easier to match to home decor.
it occurs to me that i could achieve a similar effect with a cream colored mason stain. i will still fire the piece and let you know about the results but it will have to be a little bit before i get back to you. im still working out particulars of how im going to afford my own kiln and i'm only able to fire my work at my old high school (god bless my amazing teacher). anyways, spring break. nuff said, have i got timing or what .
speaking of timing, i've run out. this is a recurring theme lately. chris, i want to address your reply and will as soon as i'm able. again thank you both so much!