new member wants to cupel

G

goldriver

New Member
#1
#1
I built an oven and went to cupel some lead buttons from a fire assay` . . . and the lead would "spit" real bad. So I thought I would ask around . . . is it better to put the lead in at start up with a cold cupel and raise the temp to 1650 f slowly . . to avoid spitting . . or is it better to bring the bone ash cupel to temp, and then place the lead in.?
Or is the spitting caused by excess forced air in the flame.
Or should I use a reducing flame to break them open.
 
fireguy

fireguy

Supermoderator
#2
#2
goldriver said:
I built an oven and went to cupel some lead buttons from a fire assay` . . . and the lead would "spit" real bad. So I thought I would ask around . . . is it better to put the lead in at start up with a cold cupel and raise the temp to 1650 f slowly . . to avoid spitting . . or is it better to bring the bone ash cupel to temp, and then place the lead in.?
Or is the spitting caused by excess forced air in the flame.
Or should I use a reducing flame to break them open.
Click to expand...
Are you trying to cupel in a gas fired furnace? If so, do you have a muffle with a separate air source? You may want to review this post about cupelling in a gas furnace:
http://www.fireassays.com/forum/viewtopic.php?f=1&t=21&p=34&hilit=oxidizing#p34
Briefly, you cannot cupel in a gas furnace in the combustion chamber as oxygen is required to oxidize the lead, and all of the oxygen is consumed by the combustion.
You should definately preheat your cupels up to full temperature, and then add your lead button to the hot cupel. Any residual moisture, either left over from the original manufacturing process, or moisture that had been picked up in storage or shipping will cause the spitting.
 
F

furnaceoven

New Member
#3
#3
Hello Everybody.

I am New Here From Outsource And Offshore Chamber Furnace Manufacturers Company. We Provide Custom Word Wide Chamber Furnace Manufacturers service as per client requirement. So if you any question about Chamber Furnace Manufacturers are welcome.

Thanks.
 
R

RavinAegis

New Member
#4
#4
Hello Furnaceoven,

I will sure contact you when I need your help.. Thanks for your introduction. It will help to others also..
 
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