raku glaze

[fay144]

Hi All,

I've not done any silver clay work yet. Most of my jewellery so far is in traditional metal working techniques. I've booked onto a silver clay class in a few weeks, and decided to get a book from the library to read first. It was one by Tim McCreight, and included a "50 projects" section.

One of the projects involved making a silver clay bead, firing it, dipping in a raku glaze for ceramics, firing again to melt the glaze, and then using the standard raku techniques of cooling in sawdust or similar.

It looked amazing, and this is something I am interested in trying... has anyone done it? I've done some searches, and only found one other website discussing doing this, again, for silver clay.

My main question is - does it need to be silver clay? Surely, since the steps involved firing the bead first before glazing, it is then just fine silver, so any silver piece could be treated in the same way?

Interested in hearing any experiences people have had with this!

Does anyone know how raku glazes differ from enamel? I've done raku firing of ceramics once, but didn't really pay too much attention to the glazes.

[Dennis]

Don't know Fay, but what was the tile of Tim McCreight's book please? The trouble with books I find, is that you can't ask them questions.
Kind regards, Dennis.

[fay144]

Very true Dennis! I love having access to a university library for a great range of jewellery books, but sometimes a quick word is worth so much more.

I don't have the book here, but pretty sure it was "Precious Metal Clay Techniques".

I've found some interesting stuff about raku firing of enamel while I've been looking into this, so I'm tempted to just give that a go at some point as a start... might buy a fire extinguisher first.

The raku glaze pictures in that book were very intruiging though.

[fay144]

Actually, tell a lie, the book was "Working with precious metal clay".

[Dennis]

Aha, I could tell by your face. Actually, I'll have to give it a miss as I don't fancy 50 projects in clay. Maybe Murano Silver, or Miz George will chip in with an answer for you if we keep this thread simmering. Can you simmer a thread? Dennis.

[jille]

Hi Fay, I have that book and the same project took my eye, something I must try out one day. Like you I did a raku course that only lasted one day as the teacher had a bad back. I will get back into raku one day though, I was looking at making raku beads on youtube last week. if done a bit of raku on copper enamels too.
I think he is using raku glaze for ceramics, I can tell you the little I know about glazes, overglaze enamel and copper enamels, basically they are similar but not the same. I would imagine that they all have different coefficient of expansion which could cause cracking and crazing if they are not compatible with the body they are applied to. Raku glaze must be fairly robust tho when you think of the treatment a raku pot goes through.
Oh now you have me wanting to order some raku glazes, and I've too much to get on with just now.
I'm looking forward to seeing how you get on.
You can buy raku glazes from Bath Potters , not that expensive
http://www.bathpotters.co.uk/searchresults/processsearch/raku/0-0-0-0-0-0-0-0-0/1

[fay144]

Thanks for that, it's very helpful - you are right, the glazes aren't that expensive, so well worth a bit of experimenting, I think...!

I'll come back and post the results when I've finished.

[jille]

This is wandering slightly off topic really, I have wanted to make some raku beads for a while. I need to make a frame to hang them from, the one I saw was made from steel angle brackets but all i can find are galvanised. Does anyone know where I might buy some, or is it possible for me to make something from steel myself? I'm hoping Peter and Dennis might have some suggestions
thanks

[Goldsmith]

Hi Jill,
I have a workshop full of useful bits and pieces, let me know what you need or send me a sketch with sizes and I will see what I can come up with.
James

[jille]

Thanks James I have e-mailed you

[ps_bond]

Ah, it's for firing? The zinc will fume off, and in sufficient quantities can give rise to metal fume fever (yes, it's a killer) - so there's your poisonous gases. Horrible stuff. Oh, the zinc oxide also deposits onto everything going, contaminating welds, glazes, everything.

However... If galv is all you have, you can (relatively) safely pickle the zinc off using acid - I've used brick cleaner from B&Q, 10% sulphuric or vinegar on occasion, the vinegar being the slowest; it will fizz and generate hydrogen as the zinc reacts with the acid. Once the reaction stops, I add a small amount more acid and see if there is any zinc left to react.

In the case of sulphuric acid, the resulting solution is a mix of the acid and zinc sulphate, not much worse than used pickle really; the steel will need to be washed and preferably neutralised in e.g. bicarb, but it'll be clean of zinc.

Zinc fuming shows as a white smoke at heat - you'll see it if you melt brass, get it too hot and more fumes off. Solder contains some, but in such small quantities that proper ventilation is aduquate. You can burn it off in a forge, but it is a really, really unwise thing to do - here's an object lesson: http://www.anvilfire.com/iForge/tutor/safety3/index.htm

Usually caveats - handling acids, alkalis, generating flammable gases, ventilate, working at heat etc. etc.

[jille]

thanks peter for all the info, i certainly won't be firing glavanised steel!!

[PureGold]

Wonder if these might help you as they seem to do metal bead racks for raku kilns...http://www.ceramatech.co.uk/6.html

[jille]

thanks for the link, I have saved the website, those bead racks look good but I can't find the prices.
I just want to mention as i see they sell Nabertherm kilns, I have had no end of trouble with mine from the day i got it.

[fay144]

Hi, just wanted to update this with my results so far.

I had a go at using raku glaze, totally unsuccessfully. I tried it on copper, and the glaze just chipped off after firing. I didn't really want to waste any silver, and figured it would be the same as copper. It must be something about the nature of silver clay that lets the glaze adhere better. I'll give it another go when I get round to getting some silver clay.

On the up side, I tried raku firing enamel while I was setting fire to things anyway... that was more interesting, if a bit frustrating. I had one really good result with a green enamel, but struggled to repeat it. I had a few ok results, and the rest were largely unaffected by the raku process. It was an interesting afternoon regardless though, even if it didn't produce any master pieces.

[Kwant]

Hello Fay, sorry to hear things did not go as expected, perhaps it is the slightly porous nature of PMC that gave better results. Having said that, I am slightly at a loss as to why you would even want to raku fire silver, as in my experience of using ordinary raku clay with raku glazes and oxides they often give beautiful metallics in any case and I cannot quite see the point of trying it on silver in the first place. Do you have some pics of what happened with the precious metal clay?

[jille]

I'd love to see pictures too.
The silverclay piece in the book looks lovely, it made me want to have a go but I am playing with clay for the next few weeks.
I did some raku on enamelled copper and after a few pieces i managed to work out how to get a good effect but as i didn't keep notes I'll have to go back and start again, My enamelling kiln doesn't have a pyrometer so it's hard to know the temperature so it's a bit hit and miss for me anyway, i quite like that though.

[fay144]

Kwant - sorry, I've tried to find the photo from the book that I could post, but can't find a copy online. It was a very interesting effect - in the project in the book he created a donut shaped hollow silver form, and then dipped it in the glaze, so less than half of the surface was glazed. It was a very different effect to enamelling. It seemed worth a go.... I think you are right though, it must be the porous nature of PMC.

Jillie - yes, I'm definitely going to give the raku enamelling another go at some point, and I agree that unpredictibility can make things interesting sometimes! Did you use sawdust, and how long did you leave the piece in the sawdust for, if you remember? I wasn't really sure if I was leaving it long enough...

[Kwant]

Np Fay thanks for looking, as far as how long to leave things in the sawdust, leaves what have you, it is the fire and smoke caused by the hot piece being put into the combustible material that causes the effects so as soon as the fire is out and the smoke is gone is long enough.

[jille]

I used newspaper and a tin lid for the copper pieces. When I did raku bowls we used sawdust. i think it's good to try different things, we got flecks on the pots where the sawdust landed on them, not sure that would be a good look for copper tho.
I have ordered clay and raku glazes from Bath potters, i can't wait to use my new bead rack out. I might play with porcelain while I'm waiting

[jille]

I was looking at my book at the weekend and noticed it has a picture of the raku glazed silver pendant on the cover, it's at the bottom of the cover.
http://www.amazon.co.uk/gp/product/images/0713658282/ref=dp_image_text_0?ie=UTF8&n=266239&s=books

The instructions say it is fired before glazing so I would have thought it would work on sheet, but I'm no expert. I might have a go on some copper just to see what happens. I'd imagine you have to get the glaze on at the right thickness, I have used brush on glazes before and you add several coats to get the right thickness on ceramic pieces
My glazes have arrived so I'll be having a go soon.

[Kwant]

Thanks jille I get the idea now, it certainly seems to have that characteristic metallic purply colour you often get with raku.