Is cobalt blue a china color?

This all depends.  Cobalt was one of the first colors and is made by Northstar and Glass Alchemy.  But China does also make it.   Many blowers will use the China tubing to put colors over it like dichro.  It is affordable and the only tube on the market.

Why does chinese boro have a bad rep compared to american boro?

Prejudice is the answer, but there are many reasons.

Their labor is so cheap, no American worker can compete.  Glass is glass, so where it is made only means who eats from the work done to it.

There are things to take into consideration also.  Where taxes paid, many garage glassblowers do not pay taxes and take advantage of the American system.  The end consumer only has so much money, and they may not want expensive glass, if they do not understand what make it cost more.  This is your job to educate the consumer with why buy American glass.

Why are male joints no longer in style

This was a time when dabbing first came on board and there was a thing called a nail.  The nail sat in the male joint.  The issue also was that the oils are so sloppy, they would drain down and on the outside of the rig.  They also look bad.

Can you clean glass in the kiln?

yes and no.  Sometimes even water can leave mineral and they will leave what looks like a water stain on the glass.

But sometimes Elev8 will clean glass with the kiln for speed and on pieces that they are not worried about water marks inside.