Focal Bead Repair

Gail Kops · #1 2015-02-03, 12:47pm

Hey all...

Want to pick your brains a bit.

I have a focal bead that I would like to try to repair by ramping up slowly in the kiln to annealing temperature and then taking it out and briefly introducing it into the flame (small scratch/crack in the surface). 104 glass..

Have any of you tried that or is it even possible?

It was made on a 2mm mandrel. The hole has been cleaned out, but I can't get another dipped mandrel in there.

Thanks for any suggestions!

RSimmons · #2 2015-02-03, 1:30pm

You'll need to take it higher than annealing temp or it's likely to break. I'd go to 1000-1025 at least and still introduce it to the flame carefully on a boro punty with a schmear of 104 on the business end.

Robert

2xMI · #3 2015-02-03, 1:45pm

Can you try thinning your bead release and using a 1/16 mandrel?
When I've repaired a bead I hadn't removed the mandrel, so I didn't have the same issue you're dealing with. Good luck!

Mimi

Gail Kops · #4 2015-02-03, 2:58pm

Thanks to both of you.....

I don't believe I have any boro rods, Robert. Think I will try to thin some release and attempt that route.

I work in Celcius, so will take it up to 550-560. Should I hold it there for a while before i work on it?

Anyone have a slow ramp up program to do this?

Thanks!

RSimmons · #5 2015-02-03, 4:51pm

Depending on the size of the bead you'll want to let it soak for 20-30 minutes to get it hot evenly, all the way through. You could try using a mandrel with a dab of clear on the end as a punty, just make a little flat blob on the end of a hot mandrel and touch it down on the bead for a cold seal. Just don't get it hot enough to fuse. You should be able to tap it off when you are done. I don't ramp up, just put things in and turn the kiln on, but the kiln I use for this sort of thing is firebrick and doesn't get hot that quickly, maybe 30 minutes to full heat.

Robert

2xMI · #6 2015-02-03, 7:15pm

Gail, don't forget the mandrel will be hot so be prepared to use Kevlar gloves or something to hold the mandrel with when you remove it from the kiln.

Mimi

ingetraud · #7 2015-02-06, 9:06am

You could try using a tungston rod to hold it. I think Arrow Springs sells them.

RSimmons · #8 2015-02-06, 10:26pm

When taking a hot mandrel out of the kiln I use long needle-nose pliers to grab it near the bead. I then stick the handle end into a tall glass of water. This cools it very quickly to a temp that you can hold ad the bead stays hot so long as you don't dawdle about. Much easier than trying to handle a hot mandrel with gloves.

Robert

Ravenesque · #9 2015-02-07, 1:52am

I believe there was just a thread on this so check there too. I sadly have had to do this too much lately. *long story. But I don't up my temp, I just have it so the mandrel is sticking out and then carefully reintroduce. I've fixed cracks and pieces of stringer I've banged off.

Oh and if they are off the mandrel already, I just clean the hole, dip a mandrel and slide the bead on carefully. Let it dry and I take a brush and clean up around the hole.
Wait, why can't you get another mandrel in it if it's been cleaned? It should be bigger then. If it's too big you'll see when you put it back onto a dipped mandrel the release will fill any space.

RSimmons · #10 2015-02-13, 7:17am

The problem that most people have with putting a new mandrel in a cleaned bead is in keeping the area immediately around the hole free of release. If you can get it clean down close to the mandrel and be careful to not get the bead too hot in that area it works fine.

Robert

artsyuno · #11 2015-02-13, 8:45am

I find that it's easier and cleaner to put the bead on a mandrel that has dry bead release on it. It won't adhere as much, but to repair the bead surface (vs all the way down to the mandrel), you don't need it to adhere as snuggly. You don't even need the bead to slide all the way on. If you can get the mandrel far enough into the bead hole that it'll stay still while you work on it, that's all you need, because you won't be getting the bead at the mandrel hot enough to run. I agree with Robert, that it's much easier to do repairs if you heat the glass to somewhere in the boro range and give it a good soak first.

Magicfire · #12 2015-02-14, 10:11am

I second the dry bead release! I do this all the time. If the bead is already cleaned and it has a scratch or something, I just slide it on a mandrel with dry bead release on it and made sure it won't move around.

I have mandrels of different sizes, and just try different ones until I find one that fits.

I also do what Robert does and dip the mandrel end in a tall glass of water.

Someone else in another thread said they grab it with a folded-up wet paper towel. That would accomplish the same thing as the glass of water, but would be quicker (I've been meaning to try that...).

I don't change my ramping temp and I haven't had any problems. I garage at 960 degrees and it's usually been soaking a while before I pull it out. I'm not talking huge beads here, though!

Quote:

Originally Posted by artsyuno

I find that it's easier and cleaner to put the bead on a mandrel that has dry bead release on it. It won't adhere as much, but to repair the bead surface (vs all the way down to the mandrel), you don't need it to adhere as snuggly. You don't even need the bead to slide all the way on. If you can get the mandrel far enough into the bead hole that it'll stay still while you work on it, that's all you need, because you won't be getting the bead at the mandrel hot enough to run. I agree with Robert, that it's much easier to do repairs if you heat the glass to somewhere in the boro range and give it a good soak first.