Slag on Springs??

[kent]

Hi guys. Was just wondering if anybody ever seen this before. Took apart my springs on Saturday and sand blasted them, then epoxy primed them. Seen a bit of something on them but didn't really notice anything until we put the first coat on them yesterday. My body man let them dry and I went out to see them today. We took the DA to the worst section to see if it was a reaction or something. When we got down to bare metal you could see it. It looks like slag when the springs were made?? Any Ideas? Would there be a way to fix it? Sure most of it is hidden but just wondering if high build primer would work on a spring?  I was kind of wondering about the pitting also from rust? I'm kind of disappointed with them.
Thought I would bend your ear.
Here is a few shots of what I'm talking about.

[BLK 68 R/T]

Admittedly I've haven't disassembled that many leaf springs before, but I can't say that I have seen that on any that I have taken apart. Maybe what appears to be slag is actually the good surface of the spring and the other areas have been corroded away by rust?    Have you taken a heavy scraper or a chisel to it and see if it flakes off?

[kent]

Thanks for the reply BLK 68 R/T.  I don't thinks so. That stuff is one with the spring. I can see the difference where the pitting from rust. The car only has 23k on her and spent most of her life under cover. A chap over at FBBO said he used to work at a foundry and said he used to see this on hot rolled spring steel. And apparently I have a very bad or good example of this. Just my luck. For the time being I going to live with this as much of this is hidden by the next spring.
Once more thanks for the reply.