DIY reblueing effect on value

[Atom]

I have a Walther PPK/s bought new in the mid 80s. It has been stored but not sealed and has developed some spots of cosmetic rust on the frame and slide. Otherwise in perfect condition. I bought a blueing kit but have been told by two different old hands at the range that it is a collector’s item and the reblueing would decrease its value. Opinion? 

[KahrMan]

It would lose most of its value for collecting if you reblue the spots. The rust spots will decrease the value some but the reblue will drop it even more. 

[Grayfox54]

Yep, despite what some people think, a refinish always lowers the value of a gun. Unless the damage sticks out like a sore thumb, just clean it up and leave it alone. 

Another option is to contact Walther USA in Ft. Smith, AR and see if the will and what the cost is on a factory refinish. I don't know if they offer this service, but it won't hurt to ask. 

If you just can't live with it and want to do it own your own, you might try just a spot touch up. Clean up the rusty spots. If not too bad or large, you might try touching up those bad spots with cold blue. However, be very careful as most cold blue solutions will dull or even damage the factory blue on the rest of the gun. That depend entirely on what blueing solution and method was originally used. First clean the area with some sort of degreaser.  All oil and dirt must be removed from the metal. Ordinary plain alcohol will work. Rinse with cold water and dry thoroughly. DO NOT TOUCH IT WITH YOUR BARE HANDS. Just the oil on your skin is enough to mess it up.  Put just a little bit of solution on a Q-tip and apply only to the damaged area. Repeat as needed to match the original finish. When done, apply a good coat of oil to neutralize the solution. Otherwise, the rust will come back. 

Post some pictures and we can give you much better opinions.