Egyptian Paste (aka Faience)

Experimenting in all facets of Egyptian paste, mixing clay, construction techniques, firing solutions, and finishing ie. cold working is in the scope of our discussion. Perhaps we will have time to get around to some practical uses of Egyptian paste, but mostly research into what works will with this media and what does not.

Tuesday, August 03, 2010

A curious effect

Hi Anitra,
I have a noticed in my last 2 firings that quite a few of the beads have an unusual, yellow, fluorescent sheen to parts of their surfaces. It seems to be appearing on the paler colours - either the plain beads (with no colouring oxide in them) the pale turquoise beads and some of the beads with rutile as a colouring oxide.
It is quite unsightly and I am at a loss as to what is causing it and how to rectify it. I remember this happening on a random basis years ago.
I do not think it is being caused by the salt in the water as it has not occurred during all recent firings with salt present.
It only appears on some beads on each of the wires - others on the same wires are yellow free.
I feel it could have something to do with a reaction with the nichrome wire somehow and it is flashing onto the beads. It seems to be most obvious on the tops of the beads and at the holes.
I have bought brand new wire and threaded almost dry beads onto clean wires to test if it was happening during drying and it still occurred.
I have noticed it appear at times while making the beads - so it is present before firings. It seems to appear it of no-where.
If I look closely at the gaps in the wire between beads pre and post firing I think I can detect a small amount of greenish/yellowing on the wire.
Hmmm very curious and if anyone has any thoughts I love some help please.


Blogger BlueTerracotta said...

Hi! I just discovered your blog and it's so interesting to find people who work with Egyptian paste. I recently tried two recipes and the objects came out pretty, but there was a lot of sticking. What kinds of stilts do you recommend? I did a blogpost if you want to see my results:

11:54 AM  
Blogger anitra said...

Yes’m, Kriket, glossy beads will stick to the wire and it's reasonable to assume that the nasty yellow stain is coming from the nichrome wire. Why doesn't it happen more often is the question.

Try this: clean your nichrome wire with a pumice stone or stilt mark remover stone. You notice a greenish residue coming off, that's chrome; in low concentrations it will give you a rather yellowish tint, complex with tin oxide it's a nice pink blush. I digress. Anyway, back on subject, coat your wires with a wash of Whiting or kiln wash, let dry, of course. You could dip the coated wire in hot wax or a wax-resist emulsion if you are stringing wet beads onto them, only if you desire. Be sure your hole is amply large to allow for shrinkage. It's more work, I know, but in all likelihood it will cure the yellow staining.

Just to prove to yourself that the nichrome wire is the culprit for the yellowing save powder you scraped off the wire, mix it with a little water and paint it on one of your beads then fire. You will find you'll get a uniform yellow color. Oh yeah, take pictures and report back in.

I'm thrilled to have you posting. Welcome on board!! ------------ Anitra

6:05 PM  
Blogger kriket said...

Hi Anitra,
Thank you for that! I anticipated I would need to coat the wires with something - will try the whiting first and will also do the little experiment with painting the bead. Making beads today and tomorrow - so firing later in the week - will post results on the weekend. Fingers crossed

5:32 AM  

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