I have a 1920's Belgium proofed 16ga SxS with a thumb print sized spot on one barrel.  It is not rusty or pitted, just much lighter colored than the surrounding area.

I have tried various times to thoroughly clean it with 90% alcohol and then use PermaBlue paste to touch it up - following the instructions I think.  Any suggestions on methods for touch up?  Because this spot comes back no matter what I do and it's ugly.



ETA:  Appreciate the help guys.  Used the Oxpho-Blue from Brownells.  Seems to have done a better job.  It isn't perfect, but you can't really notice the spot unless you look close now.

have you tried oxphoblue from Brownells?

How are you applying it?

No, I used Birchwood Casey PermaBlue paste.  I applied it by dabbing a little on the end of a q-tip, and the dabbing the q-tip into the light spot.

I've had more luck with BC Super Blue, apply bluing, heat, remove with rag, repeat. After that gun oil.

Try Oxphoblue since the other isn't giving sat results.  For stubborn spots, here how I do it.  Degrease the area well.  Apply heat it until it's just barely too hot to touch.  A apply a small amount of Oxphoblue with a Q-Tip or something.  If it bubbles a little and you see a little bit of steam/smoke, that's no big deal.  Lightly buff the area with 0000 steel wool for a few seconds or until the Oxphoblue is gone.  Repeat until satisfied.  Good luck.

Thanks guys.  Never knew about using heat.  Went ahead and ordered some Oxpho_Blue, and I'll try heating it this time.

Appreciate it thank you.