View Full Version : PMC - am I not firing it enough
08-09-2009, 08:49 PM
I have only been working with PMC 3 for about 2 weeks, have made a couple of pieces and they seem to have come out okay. I made a piece which my DH likes so I have kept it for myself and have worn a couple of times.
The problem is that it feels rather soft, it bends very easily and a piece has broken off :-O. I bent this piece in between my fingers and it broke in half like a twig - what am I doing wrong? Any help would be appreciated.
I have pics but cant seem to upload them at the mo!
Also while I am at it, how do you get them to shine so nicely. My hubby made me a tumbler at the weekend but have not tried it yet as I need to get the shot (if that is the correct term (?)), is this the only option to get them shiny? I used my dremel bits, the cone felty thing as well as the soft round cloth. I did not use anything with them, ie. polishing agent and the result was not as good as I had hoped. I am cautious about over working the article in case I do damage to it in any way - can you over work a piece of pmc silver?:(
Sorry for the incorrect terms and all the questions, I am still learning all the correct terms and what to do!
Thanks in advance for your help!
08-09-2009, 09:08 PM
I'll try and help but can you answer a few questions so I can narrow down some answers for you :)
1) What is the piece you made
2) How long did you fire it and by what method (e.g. Torch/Hob/Kiln)?
3) How thick did you make it 1mm 2mm thicker? thinner?
4) What finishing are you doing prior to firing?
08-09-2009, 09:28 PM
Ah thanks for coming back to me so quickly.
1) It is a pendant; will try and describe it, I cut three long strips (4cm) and placed three smaller stips (1.25cm) interwoven with each other, similar to a basket weave style, there are gaps in between the strips and placed a cz in the middle.
2) I use a torch, I made sure that it dried for longer than usual - 36 hours. When I torch then I make sure that it glowes orange for a good 2 minutes moving the torch around the pendant.
3) I would say it is 3mm at the thickest part and 1mm at the thinest part - this is the bit that broke off
4) Before I cut the clay I used a pattern similar to a lace pattern but it did not indent the clay that it impaired the thinkness or weakened it in any way.
After it was fired I left it cool down on its own and the used the brass brush, then the brass dremel bit then polished it up with the 7 polishing cloths that was recommeded when I bought the kit. It did not come up shiny as the others and it was the same pack of clay that I used before.
Thanks Nic, I hope that I have given enough info.
08-09-2009, 10:03 PM
Angie you can post pics direct after 15 posts, meanwhile put them in your profile album
IMHO the piece might be a wee bit big to torch fire successfully (the US recommends not bigger than a nickel for torch firing). But Nic is resident expert (I use a kiln). Pics would make it easier to tell. Ends would certainly be vunerable but 1mm should be OK.
08-09-2009, 10:06 PM
Fine silver is weaker than sterling and 1mm fine silver would also be quite bendy, (though probably wouldn't snap as readily as PMC/ACS) ;). Fired silver clay is a little weaker than fine silver (as it's less dense & more porous).
To see if it's fired to the max have a look at the broken edge, if it looks "flaky" then it could do with being fired again. Re-fire in a dim room hotter & longer. Melt a scrap bit first (to set the melting point colour in your mind) & take it as hot as you can without melting it. (Sorry if this is teaching Granny how to suck eggs)
If you want to fix the break then you could use Lavender paste (do a search on my PMC tips blog if you haven't got any and need to know how to make it). You could also add a thin back piece or an edge to strengthen the design.
Do as much finishing as possible in the clay stage, it's quicker and will give better results. Don't use sanding things on your clay that have been used on the metal and visa versa. Sand smooth then very gently go over with a baby wipe, this leaves a beautiful smooth finish that will take a good shine.
Once fired I brass brush the piece using a little washing liquid as lubricant (this reduces the fine scratches that the brush leaves). Two brushings might be leaving scratches on your work and making what is effectively a matt satin finish, check and see next time you brass brush :)
I then use the rubber burrs that cooksons sell brown (fine) and green (extra fine)
followed by either the white polishing pads or wenol and a polishing cloth. They both give lovely finishes...
Hope that helps
08-09-2009, 10:28 PM
Thanks Em and Nic, I shall certainly try your suggestions. My hubby is facinated by this and asked the other day at what stage it would melt, I shall certainly try this tomorrow. Looking at the broken piece in more detail, it looks gray/white in the centre of the break.
Nic, I am a granny, and youngish one though - LOL! Dont worry though I am open to any forms of suggestions and advice. This is all new to me and am more than willing to listen and learn and learn from my mistakes.
I am sure there will be tonnes more questions to come and I am sure there will also be more head bashing to do as well. I spend more time googling things than what I do making things at the moment.
Thanks once again.
08-09-2009, 10:35 PM
Grey white in the centre normally means it could do with more firing :)
08-09-2009, 10:43 PM
Thanks Nic - really appreciate your help.
09-09-2009, 09:31 AM
Silly question - can you paint the broken edges with slip, stick them back together & refire? If so, at what point would that stop working - can you do it to fully-fired stuff, for example?
09-09-2009, 09:37 AM
If it hasn't been fired then yes you can paint the broken edges with slip or syringe paste, join and refire. For fully fired stuff you need to use either commercial oil paste (available to buy from Silver Clay suppliers) or Oil Paste which you make yourself (usually Lavender oil).
09-09-2009, 11:24 AM
can I offer a quick plug for Cooksons?
Art Clay Silver Oil Paste - 10g - Cooksongold.com (http://www.cooksongold.com/product_detail.jsp?prod_search=855072)
09-09-2009, 11:45 AM
Well done Rob!! Oil paste lasts forever and is designed for the job.. :Y:
09-09-2009, 12:26 PM
Out of interest can you use it on Fired PMC as well as Art Clay?
09-09-2009, 12:57 PM
Yes, its all fine silver once fired. Oil paste is soooo handy. (bit smelly though!)
09-09-2009, 07:40 PM
I have some oil paste so shall have a go - thanks for all your help.
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