On Sat, 22 Feb 2020 16:34:11 -0800 (PST), Christopher Tidy
wrote:

Am Samstag, 22. Februar 2020 16:43:47 UTC+1 schrieb Ned Simmons:

Replying here because I had to open your reply in Google groups...

Sorry. I've been using Google Groups since my last machine with Netscape 7 died.

Yes, that's essentially how they're used. If you look into it you'll
find endless advice on how exactly to spread the blue, how thick, how
to wiggle the master, etc.

They do have some value. Search the sold listings on ebay for
"camelback straight edge".

I think I might keep the masters now. I might like to use them one day, and they're rather attractive.

Any idea what brand of scraping tool is good, and how much a tool would cost? I'm guessing scraping works much better on cast iron than mild steel. Is that right?

Best wishes,

Chris

For scrapers see:
https://www.mcmaster.com/metal-scrapers

For use... almost anything. Scraping bronze and babbet bearings was
considered a skill in the old days :-)

When I was working in the trade I kept a small triangular scrapper in
my tool box for deburring the edges of holes (along with an 8" double
cut file for deburring outer edges of things :-)
--
cheers,

John B.