I bought a used 1990's steel bike the other day and have disassembled it for repainting. However I came across a small patch of missing paint on the drive-side chainstay, which had apparently been removed to check up on a small hairline crack. It doesn't seem like an immediate safety hazard, but I'm concerned it will continue to grow.
Having the frame professionally repaired would probably be prohibitively costly, so what are the DIY alternatives? The best solutions I could come up with is to either use epoxy glue and steel strips to reinforce the area (but epoxy is apparently not ideal for some reason), or drill two small holes at the end of the stress crack to prevent further propagation, then fill in the holes somehow. I do have a soldering iron, which I'm pretty sure isn't a recommended solution.
Any advice is appreciated. Thanks.