I've just had my first proper try with reducing some DH to a metallic finish (Triton, Psyche, Aurea). Worked wonderfully I thought. But after annealing a lot of it has gone - often on the same side across the mandrels - but a bit randomly in some cases. I am batch annealing as for Effetre in an SC2 kiln.
Any ideas anyone please?
Thanks
Helen
Okay - I am not an expert on this and I am sure there are others here that probably have more experience on this subject - but I had this problem too and this is how I fixed it. Silverlemon (Sarah) helped me solve this.
I don't have an SC2 so can't really comment on annealing temperatures across this particular kiln - in terms of which is generally the hotter side/top/bottom etc, but you may need to make sure your kiln is not getting too hot in the annealing cycle, I have heard that this can effect the finished results of silver/metallic glass.
Also, your kiln must have an oxidising atmosphere. Try a tiny teaspoonful of activated charcoal in your kiln to create a reducing atmosphere. Put it in a tin or dish, to stop it making a mess of your kiln. Any aquatics centre will sell this.
I tried both of the above and it worked.
Good Luck.
Kerensky
Quote from: kerensky on March 26, 2010, 08:55:48 AM
Also, your kiln must have an oxidising atmosphere. Try a tiny teaspoonful of activated charcoal in your kiln to create a reducing atmosphere. Put it in a tin or dish, to stop it making a mess of your kiln. Any aquatics centre will sell this.
That's the right way to deal with it - but the kiln must have a reducing atmosphere, not an oxidising atmosphere. It's already got an oxidising atmosphere, that's why the metal lustre is going. The charcoal will "suck up" the free available oxygen instead of the metal surface of the beads. Sorry to be chemistry pendantic!! :D ::)
You have to be a little careful - some kilns with exposed elements have a special oxidised coating on the elements which protects the element. Obviously too much exposure to a reducing atmosphere will decrease the element life. I don't know so much about this - perhaps a kiln expert can elucidate.
so should i put charcoal in the kiln whenever i use 'silver'glass ...and does that include encased ???
Dohhhh....Thanks Sal for pointing that out, it was quite a confusing sentence wasn't it ? - will read it better before I click "post" in future.
Didn't know that about the Element on the kiln - perhaps I am about to be enlightened soon.....oooo err as they say!
I do use charcoal whenever I use Silver glass - but perhaps not for much longer given the info about the Element..
Once the glass is incased you shouldn't need it, because in theory it is not going to be exposed to an oxidising atmosphere.
Sal?
have a ;look at this thread:
http://envisionsf.blogspot.com/2009/04/silver-glass-101-annealing-temperature.html
Hey that is top info Shahlaa thanks flower!
Yes - Thanks for that - it is a little gem and worth printing out and pasting on the wall next to kiln just in case I have a senior moment, again!
i followed hayleys advice and lowered my kiln temp to 493c but i now anneal and hold at that temp for much longer, 2 hours i think. not had a single problem since. I have a "silver glass" setting and a normal effetre setting, both anneal the glass properly. x
Thanks for the tips and advice everyone, and for the envisions link - I will try the charcoal option first as I already have some from trying Bronzclay. If that fails I'll try reducing the temperature slightly.
Thanks again
Helen
The charcoal won't fail, trust me! ;D
The SC2 elements aren't exposed, so charcoal is fine (if you run out of it, the stuff for fish tanks is a great and economical option!). The SC2 is also a little cooler at the front next to the door hinge, that's where I put anything sensitive that might lose it's colour :D
Thats a good tip V, you should stick it in the frugal thread as well ;)
Quote from: Tan on March 26, 2010, 08:29:56 PM
Thats a good tip V, you should stick it in the frugal thread as well ;)
Funnily enough I thought that as I typed it :D
Mmm - yep - once the silvered glass is encased the type of atmosphere won't affect it - but the kiln temperature can affect encased beads, it's usually more of a problem with striking glass as opposed to reducing glass though.
I had some hollow beads with encased reduced dots of psyche and triton - these seemed to change colour (became significantly lighter) during annealing - again mostly one side of the beads. They still have some lustre (though probably a bit less) and would look ok-ish if they were the same all the way round.
So do you think this may be temperature related? My SC2 is brand new and I did wonder if its firing a little hot - I made some little flowers (Effetre/CiM) and some of them after batch annealing to 520C looked slightly misshapen as though some of the petals had slumped very slightly. It is very slight but I'm assuming that at 520C (held for an hour) you wouldn't normally see that?
Perhaps I should try lowering the temperature slightly anyway - what do you think?
Thanks
Helen
Ok that does sound a bit odd for them to be slumping at 520. I Batch anneal most effetre & cim for 1 hr on 520. For silver glass I use 493 for 2 hours and a much slower ramp down. Can u get the temp checked? Failing that try lowering it by 10 degrees x
Do you use the 493C schedule for beads where you have combined silver with effetre or other glass - is that adequate? And how about beads where the silver is encased?
Also you mention a slower ramp down with silver glass - what rate do you use?
Thanks again for your help
Helen
I got my SC2 just before Christmas and found most of my beads had kiss marks, anyhow, after a few weeks I bit the bullet and bought an infra-red pyrometer, low and behold, my kiln was running 23C higher than the kiln reading was giving. I now anneal at 504C for 2 hours and this works a treat. I also checked my beads by producing a clear one and using polarising film was able to check whether they were annealed or not.
The following place sell 5cm squares of polarising film, which is where I got mine (they're on holiday at the mo and will open up presumably in a couple of weeks).
http://stores.shop.ebay.co.uk/Consilium-Designs-Ltd__W0QQ_armrsZ1 (http://stores.shop.ebay.co.uk/Consilium-Designs-Ltd__W0QQ_armrsZ1)
The following shows how to use the polarising film:
Quote from: sublimekate on February 24, 2010, 07:40:25 PM
I have lifted this from another thread for you, it was posted by redhotsal a few years ago, if you look through old posts in newbie questions you'll find loads about annealing problems :)
Quote from: Redhotsal on April 26, 2007, 10:55:04 AM
In reply to questions as to how the polarising thing works I thought I'd put this together for people who are not sure about annealling.
You need to get a pair of polarising filters. You can use a pair of polarising sunglasses and break them up, or the fancy filters you can get for cameras (though these can be a bit expensive) or you can use that amzing research facilty - Tinternet - to source your own, which is what I did. I thought I'd get quite a few at the same time I got mine so that I could let other lampworkers have their own. So, if you want a pair, email me and I will sell you a pair for £6 inc P+P.
In answer to a previous question - yes - I do have a website, just click on the pink beads banner at the base of this thread. And yes, I was a scientist in a previous career. Optical Physicist in fact.
They only work with transparent beads so what I normally do is make a plain clear spacer type bead every now and then and pop it in with the batch of beads that I'm annealling. This will give some indication of whether the batch has been successfully annealled or not. It's a good idea to make this spacer quite large as larger beads require more soak time at the annealling temperature. Basically if your largest bead is properly annealed then you can be sure that all your smaller ones will be fine aswell.
When you look at the bead try to sandwich the bead between the two filters. Ideally you want a source of diffuse light behind you. I'm lucky enough to have a little torch type thing which I sit the filters on, but you can hold them up to a window and use daylight. A lightbox or the "white" sky that we seem to get often in the UK - bright with a continuous cloud - is an excellent light.
Rotate the top filter with respect to the bottom one and you'll see that the transmitted light starts to go from light grey to black and as you carry on rotating it beomes light grey again. If you look at the unannealled bead you'll see that it has a series of stripes radiating out from the bead hole - often in the shape of a Maltese cross. These will rotate as you rotate the filter. These are the stress lines. The more visible they are the more stress you have in the bead. A properly annealled bead will not display these lines at all it will just go from transparent to black as you rotate the filter.]
It really is a startlingly good representation of the stress lines that are in the bead. Polarisers are routinuely used for stress analysis of various objects. I have to say it gives me great peace of mind to know that there is a tangible aspect to annealling. It takes the guess work right out of it and is an excellent and vivid tool to demonstrate to your customers (if they're at all interested!) - especially if you compare your lovely annealled bead to some imported unannealed rubbish that they're raving about.
Just another way to show your customers that properly annealled beads are worth the extra pennies!
I took this advise from Sal and tested transparent beads that I'd annealed on different scedules on my SC" until I found the one that worked and didn't make the beads stick together, because all kilns can fire at different temps you really need to test your own to be sure.
Hope that helps. Kate :)
Hope you can sort it out soon as I realise how disappointing it is to start with :)
Thanks for the link Claire-Louise - that's really helpful. I will try using a polariser (I have photographic filters) and try lowering the temperature a little I think, as well as trying some charcoal with silver glass.
BTW, where did you get your IR pyrometer from (just in case I decide to get one)?
Many thanks
Helen
I put my 'silvered' beads under a small terracotta plant pot in the kiln, (next any other beads that need annealing) this seems to stop mine from loosing the silver, maybe because they are protected from the direct heat from elements. Not sure whether right or wrong, but it works for me.
Nina
Ok my batch anneal schedule for anything with silver glass is as follows and was given to me by hayley on lampwork etc I believe
ramp 1: 149
target temp1: 493
hold: 2 hours
ramp 2: 78
target temp 2:148
hold 000
ramp 3: 000
hold:000
temp:000
total takes about 11 hours and I do it over night. Was told you can anneal lower if you ramp up slowly and hold for longer. Not had any problems with beads cracking etc. I tend to only use it for surface silver glass not encased silver glass. Not used activated charcoal as was worried it would kill my kiln.
hope that helps!
Thanks Shahlaa. I will try that next time with my unencased silver beads.
Helen
definitely try that but also try the activated charcoal. for some reason, my clio doesn't like that schedule at all! it erased all the reduction on one side! so i can only assume it was too hot for clio, but i had a very detailed scroll work bead in aurae which didn't fade at all! how bizarre!