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-   -   What is my black Lauscha doing? (http://www.lampworketc.com/forums/showthread.php?t=222720)

28676bhe 2012-04-21 10:58am

What is my black Lauscha doing?
 
I am using some older Lauscha black rods and when I apply the fine silver to it, it is turning into silver glass! Looks like I'm putting a layer of DH over it.

This has only happened with a couple of the rods out of the batch, the rest have stayed black.

Not complaining, but what chemistry is happening here? Am I using one type of flame one day and another the next?

Barbara

28676bhe 2012-04-22 7:08pm

Bump up!

Any ideas on this, fellas?

Barbara

Holly 2012-04-22 10:31pm

Are you in a reduction flame?
I can get all my blacks to turn metallic with silver in a reduction flame.

28676bhe 2012-04-22 11:54pm

The flame looks like a normal oxy/propane flame, but the tip of my torch may be covering up the ports again?

Barbara

Holly 2012-04-24 9:51am

Some of my blacks do it more than others, even within the same brand. It's the metal oxides coming to the surface.
Since I work on a Hothead I'm always in a bit of a reduction flame.
I would try to go back and forth between a reduction and oxy flame and see if you can determine if it's flame chemistry.

RSimmons 2012-04-25 12:50pm

Most blacks have manganese in them. Some batches have more than others and tend to go silver on the surface. If you have a batch of glass where some does this and some doesn't it just means that your rods came from different batches at the factory and were mixed in shipping. Reducing flames will usually bring this out but some of the more extreme cases will go metallic even in neutral or slightly oxidizing flames.

Robert

susanlambert 2012-04-25 1:50pm

I had a whole batch of black like that. It was very frustrating. If you work it rather cool, it is helpful.


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