Wednesday, September 26, 2018

cross mojo

I seem to have lost it...had 8 duds in a row with an air pocket right in the middle that leaves a big hole.  This has been happening throughout all the cross casting but usually only 1 out of every 6 or 7.  Still using the same technique but I must be doing something - and have yet to figure out what subtle difference causes this to happen.  It's all magic as far as I'm concerned anyway... 67,78,70,T,B  UPDATE:  Problem solved - see the comments.

6 comments:

96Trees said...

Impurities in the metal can cause this and unless you are sure of the source then you can't really tell.

Unknown said...

A repeating fail should be contaminated contact point in mold which could be milled out.
This might be worked around but you cannot cover any contaminant - only remove it.
Bubble in casting probably off-gassing from contaminant in high heat of pour.

Unknown said...

Based on the location, it could be the result of shrinking while cooling. Maybe the fill "tube" becomes solid before the centre of the cross becomes solid, so no new material can flow in to fill the shrinking. I would would increase the diameter of the fill "tube" and maybe also make it a cone to keep more material in the fill tube, trying to keep it liquid longer than the centre of the cross.

Unknown said...

This came to mind when I saw it!

Isaiah 53:5
But He was pierced for our transgressions, He was crushed for our iniquities; the punishment that brought us peace was on Him, and by His wounds we are healed.

John Wells said...

Figured out the problem. I started using too much silver in the pours. Each cross only weighs 24 grams and I was pouring up to 50 grams in the mold. Cut it back to 30 grams and I am getting consistently perfect casts with no air trapped.

Margery Bills said...

Anthropology research said the cross was really an X and explained how they know.