ack!! the kiln cause devit on my cobalt beads! help!

DreamMuse · #1 2005-07-20, 7:32am

Hi all! I posted this at another forum, but I thought I'd ask all of you too. The more advice, the better!

I'm dying over here!! I made a huge order for someone - thirty five dark cobalt beads. They were all gorgeous going into the kiln. When I took them out, they all have that nasty whitish devit. I wanted to cry!! (I know that we should kiln anneal beads, but this is one reason that I wish we didn't have to!!)

I tried the Lysol blue trick, but it didn't work! (I checked after twenty minutes, and they looked the same. After forty five minutes, it worked a teeny bit, but not much) I have a metal working class tonight and can try putting them in the pickle. Will that work?? I don't drink coke but I could try that too if I have to, but I heard that doesn't always work well. I was supposed to deliver them today, but I can't bring them over like this!! Is there anything else I can try?

BillBrach · #2 2005-07-20, 11:43am

Exactly WHAT color number did you use and has this kiln ever been used for PMC ??

DreamMuse · #3 2005-07-20, 11:58am

Ok, I used P-246 Dark Cobalt Blue, and actually yes, I have fired PMC in the kiln. However, it's a new kiln shelf that was not used for PMC, and I don't get devit on any other color, except for dark turquoise, and occasionally light blue. So would that make a difference?

Oh, and I should add that not every bead has the devit either! and some have more of it than others... I'm feeling very sick over here. It was an excruciatingly boring order to fill.

MikeAurelius · #4 2005-07-20, 12:07pm

The problem with PMC is that it gets on the elements, not just the kiln shelf. There's been some pro and con about this, I'm not sure myself either way, but I've always thought better safe than sorry and always fired PMC in a dedicated kiln.

Also - were the beads still slightly glowing when you put them in the kiln? Did you use the right annealing cycle? Devit will sometimes happen when the glass moves as it is "skinning over", or starting to harden.

Do you have any Lime Away or similar product? Its an acid, but handled carefully, can clean up problem spots. Pour a small amount into a plastic jar and using a Q-tip, dip it in the solution, then lightly scrub a test bead. Rinse immediately to keep it from etching. If it cleans up the test bead, it is surface only adhesion, and probably from the PMC. If it doesn't clean up, it may be over the entire bead.

Were these beads batch annealed or are they still on a mandrel? I wonder if perhaps re-heating the bead in the torch flame will clean up the surface. Devit is a nasty problem and unfortunately, trying to find out what caused it can be tough.

DreamMuse · #5 2005-07-20, 12:15pm

Unfortunately, I have to batch anneal. I'm actually pretty new to lampworking (six months) and was using PMC before I started glass. I rent torch time, and she doesn't always run the kiln. But like I said, I don't get the devit on other colors, not even white, which really turns color when I have silver on it. So it wouldn't only be the cobalt that is doing this, if that were the case, right? And I haven't run PMC in the kiln since January, and have done many batches of beads. I consistantly get the gray devit on the dark turquoise, and this white scummy devit on the cobalt blue.

The beads looked absolutely gorgeous when they came out of the vermiculite. There was no sign of the devit.

My annealing program is set to ramp them up to 960 and hold, then go down slowly, I think 100 degrees per hour to 700, then 200 degrees per hour after that... I think. I got the cycle off of another forum, and since it's programmed in, I haven't looked at it in a few months.

I don't have Limeaway, but can go buy some tonight. I'm going to try some pickle at my metal working class. Any idea how long I should soak them in the pickle for?

BTW - thanks you guys for trying to help me figure this out *Smiles*

MikeAurelius · #6 2005-07-20, 12:47pm

Don't soak them. Use a Q-tip and gently rub them. Soaking them will probably start etching them. You just want to test one first to see if the problem is on the surface or in the glass itself.

How fast did you ramp up? I generally ramp up my batches from room temperature to annealing temperature in 3 hours. One problem with ramping up too fast is that you can overshoot the end temperature and quickly get the kiln to 1000 F or better before it starts to fall back.

The drop down may be a bit too fast as well - I'd slow it down. Here's the full batch program that I use for soft glass:

ambient (room temp) to 960: 3 hours
Hold 960 for 1 hour 30 minutes
ramp to 850 over 2 hours
hold 850 for 10 minutes (this is the strain point, and this allows the kiln to settle and "catch up")
ramp to ambient (room temperature) over 1 hour (it actually takes much longer than this, about 6 hours really, but it turns the controller off, and that's all that matters).

You can also ramp from 850 down at 100 degrees per hour, but I would really slow the initial ramp from 960 to 850 down to about 2 hours.

I'm thinking that if you are getting devit on your other pieces as you mention, that the problem is not the PMC (but I'd still try the lime away test to be sure), but more likely an annealing issue.

Is this a fire brick kiln or IFB (board or blanket) (like the Chili Pepper or Tool box)?

DreamMuse · #7 2005-07-20, 12:59pm

I wish I was at home, so I could give you the exact schedule. I'm not sure offhand how fast I ramp up, but the digital controller indicates that it generally stays within one or two degrees of the target temp. I have a new Sierra 360E, that has probably been fired under a dozen times total. (Well, I have probably reached a dozen by now, but no more than fifteen times.) It is the fiberboard kind, not the firebrick.

I will make those changes to my schedule though, thank you! (I'll also do a cobalt bead in my next batch and let you know if that stopped the devit from forming)

Mike, I know you said not to soak them in the limeaway, but I shouldn't soak them in the pickle either?

MikeAurelius · #8 2005-07-20, 1:25pm

No - the pickle is acid as well - use a Q-tip and gently scrub with that. Rinse immediately. If you see a difference, try scrubbing some more. I just wouldn't want to see those beads etched if you let them soak too long.

DreamMuse · #9 2005-07-20, 1:40pm

At this point, I'll take etching over the white scum *wry chuckle*

Thanks for the tips *smiles* You've been a huge help!!!!

Lizabeads · #10 2005-07-20, 3:04pm

Quote:

Originally Posted by MikeAurelius

No - the pickle is acid as well - use a Q-tip and gently scrub with that. Rinse immediately. If you see a difference, try scrubbing some more. I just wouldn't want to see those beads etched if you let them soak too long.

So can you etch beads with lime-away instead of the etching creams that are so expensive?

MikeAurelius · #11 2005-07-20, 3:49pm

Yes, it takes longer, but you can.

krista michael · #12 2005-07-20, 4:44pm

For the gray reduction "scum" you can try soaking them in THE WORKS toilet bowl cleaner. Available at wal-mart for a buck or so. From 5-10 minutes max and the gray will be gone. I don't know about the white but it might be worth a try if all else fails. I used to soak in coca cola but it took too long for me.

DreamMuse · #13 2005-07-21, 7:19am

Update! The devit is still there *sobs*

I tried to swab them in the pickle, and nothing happened. So, I soaked one for five minutes, ten minutes, finally forty five minutes. It made the whitish part a little better, I think. It still looks rough, but not as white. The pickle didn't affect the shiny parts of the beads at all.

Limeaway didn't do anything.

I'll go to Walmart and look for "The Works" *S* Thanks, Krista! I'm also going to try Whink. I'll try almost anything at this point!!

BillBrach · #14 2005-07-21, 4:03pm

'Lime Away' and 'CLR' (and I'll bet 'The Works' too) are a WASTE of money because they DON'T work.

Only over the counter thing I've found is Whink "Rust Stain Remover" in the brown bottle. It contains Hydrogen Flouride, which is the ingredient that works. Fifteen seconds is the MAX I run my beads in Whink. I accidently left some in for a minute, and they were nicely etched !!

You might try looking at bottles of stuff at the grocery store, and see if anything has some sort of Flouride compound in them.

Sandpebble · #15 2005-07-21, 5:23pm

Quote:

Originally Posted by BillBrach

'Lime Away' and 'CLR' (and I'll bet 'The Works' too) are a WASTE of money because they DON'T work.

Only over the counter thing I've found is Whink "Rust Stain Remover" in the brown bottle. It contains Hydrogen Flouride, which is the ingredient that works. Fifteen seconds is the MAX I run my beads in Whink. I accidently left some in for a minute, and they were nicely etched !!

You might try looking at bottles of stuff at the grocery store, and see if anything has some sort of Flouride compound in them.

Actually "The Works" Really does work...and well. For me anyway. It really brightens up some colors.

Pete

BillBrach · #16 2005-07-21, 6:10pm

Pete,

What is the full name of "The Works" and who manufacturer's it. I cannot find a MSDS, to confirm its ingredients.

Bill

Sandpebble · #17 2005-07-21, 7:12pm

Quote:

Originally Posted by BillBrach

What is the full name of "The Works" and who manufacturer's it. I cannot find a MSDS, to confirm its ingredients.

Their products contain either hydrchloric or hydrofluoric acid, depending on the application.
Here's their website.
http://www.theworkscleans.com/default.asp

BillBrach · #18 2005-07-22, 3:41am

They don't have MSDS posted on their web site. Do you have any idea which contain hydrochloric and which contain hydroflouric ??

Sandpebble · #19 2005-07-22, 6:16pm

The toilet bowl cleaner is hydrochloric, the tub and shower cleaner is hydrofluoric as I remember.

krista michael · #20 2005-07-23, 4:35pm

I use the toilet bowl cleaner version of the works. I didn't even know they made other stuff. I never thought about it!