Problem firing Fast Fire Bronz Clay

[Donna@Rockin' Beads]

I fired Bronz Clay Fast Fire for a customer today. The instructions (as I understood) said 1 hour ramping at 829 then hold at 829 for an hour.
I did this, fired it in charcoal as per instructions but had to open the kiln and start letting it cool enough to take out after about an hour.
The problem is it hadn't sintered properly and unfortunately I only realised when I took her best piece and started brass brushing it to see if I could get a shine on it. It broke 
I am hoping I can repair it and it was a trial for her so only a simple heart with a thumb print, however, even if I can fix it, will it fire properly next time?
Does anyone have any experience of fast fire bronzclay?
My Paragon SC2 has always fired BronzClay (for 10 hours) with no problem but I did have CopprClay fire badly and not sinter properly before.
I am going to trawl the web and will probably hold it for 3 hours then let it cool completely before getting it out but I thought I'd ask here anyway as you guys know so much about this stuff 

Thanks 

[rocky]

Hi Donna
I use fastfire bronzclay, bronzclay and prometheus (among others). My fave is the fastfire cos you can actually whip one steel tin out of the kiln and pop the next one in. Much more productive. The clay is a bit more 'leathery' but it works well.

As for holding times, I always err on the side of caution and I add 50-100% hold time to all recommended fire times. I only place pieces on the back 2/3 of the firing tin too. I have had pieces not sinter before. Luckily, they were for me.

I am doing a whole batch of bronze clay things at the moment. I will post them up when they are done.

Good luck with the mend. I think, with some thick paste you could fix it. TBH, I haven't tried a mend with it yet. It only shrinks by a bit too (not like the bronzclay!!), so it should be OK.

[Donna@Rockin' Beads]

Thanks for the quick reply.
I made sure I had everything in the back of the tin and you've answered my concern about cooling too quickly.
I've never had any success with fixing and have a feeling I'm not going to today 
Do you have any idea why your pieces didn't sinter?

[rocky]

Thanks for the quick reply.
I made sure I had everything in the back of the tin and you've answered my concern about cooling too quickly.
I've never had any success with fixing and have a feeling I'm not going to today 
Do you have any idea why your pieces didn't sinter?

Yes, it was copper clay and the pieces were quite thick (from 2mm up to 6mm in places). I followed the recommended fire times and .... I made biscuits - at least, they snapped like biscuits!! After that, I used longer fire times. Probably overkill but it doesn't seem to cause any issues. Also, for thicker pieces, if I can, I often make smaller components and solder them together afterwards.

[poledra1958]

Hi Donna
I use fastfire bronzclay, bronzclay and prometheus (among others). My fave is the fastfire cos you can actually whip one steel tin out of the kiln and pop the next one in. Much more productive. The clay is a bit more 'leathery' but it works well.

As for holding times, I always err on the side of caution and I add 50-100% hold time to all recommended fire times. I only place pieces on the back 2/3 of the firing tin too. I have had pieces not sinter before. Luckily, they were for me.

I am doing a whole batch of bronze clay things at the moment. I will post them up when they are done.

Good luck with the mend. I think, with some thick paste you could fix it. TBH, I haven't tried a mend with it yet. It only shrinks by a bit too (not like the bronzclay!!), so it should be OK.

Do you know where I can get the prometheus bronzclay from my kiln is not big enough for a charcoal holder so I can not try the other one