Re-bluing questions

I picked up a kit to re-blue my 1911. I read thru the directions and it seems pretty strait forward. I guess my only question is why do I have to remove ALL of the prior re-bluing before I add more?

My 1911 is worn in some parts where it comes in contact with the holster/hand etc... All I really want to do is touch it up. I don't want to "de-blue" the whole thing just to re-blue it.

Can someone give me some ideas to do this on my own? I have everything that is needed to do it... but all I have are basic directions, and no experience. I'd like to learn how to do this, so please don't recommend to take it to a gunsmith. I really do want to try this and learn it by myself.

Thanks for the tips!

I would think that it has a lot to do with color matching then anything else.

I have some experience bluing and Norman is right, it's hard to get an even color just doing one spot at a time. It is strange trying to blue, the timing involved is IMO the most important part. You have to only leave the stuff on for less than 60 seconds (30-50) worked well for me, and use many "coats" to get the darkness that you want.

If you are hot bluing, Bluing is an oxidation process that is neutralized when finished. It also protects metal from oxidizing to some extent.It would allow the unblued metal to accept the bluing and not the already blued metal to the same degree. I would assume cold blue works in the same manner.