Believe it or not, I have used a waterproof black marker with surprisingly good results. As long as the area you are applying it to is degreased, the marker stays put quite nicely. I find that it also stays wet just long enough that you can smear it slightly with your finger to feather it onto the surrounding area.
Definitely not a permanent fix, but surprisingly durable.
(send $2.00 and I'll tell you the brand of marker !!!) :wink:
<font size=-1>[ This Message was edited by: shane45-1911 on 2001-04-02 13:11 ]</font>
For fitting of parts, I like Dykem High Spot Bluing best. It will show the interference points real well. It's easily applied, and is very visible to these +40 eyes. It is a bit messier than other options. It doesn't dry, and it will stain your fingers if you get it on them.
I've used it on everything from fitting guns, to final fitting of gas turbine blades.I've tried other things, but for fitting I like this the best.
While it's neither finish nor cold blue, I've had ok luck coating the bare steel with Shooter's Choice Rust Prevent. My project Kimber has bare metal all over it, and no rust. This is eventful in the humidity of S. Florida. I used cold blue with good results, but found it laborious for something that was going to get removed again in short order.
Here's another twist- If I don't have time to fire up the hot blue tanks, but need to protect a bare steel part I "hot/cold" blue it. Started doing it many years ago on sights I had just worked on. Degrease thoroughly, glassbead if wanted (works great with a removeable/dovetail front sight) heat with a propane torch - probably 400 or so degrees - and lower into a pan of Brownells Oxpho-Blue. Make sure it's quickly and completely submerged. After a few seconds lift out, wipe off and oil. Nice and black and pretty durable.
Now here's the interesting part: with a complete slide, polish, degrease, and with a wire hanger supporting it, heat and dip, etc. If the basic finish is not real shiny, you get a finish that will easily pass for a hot dip blue. Works best on, say, a 320 grit finish maximum, and it's crucial to degrease thoroughly.
Great if you're going to do a few weeks' testing on a gun before final finish, but for a do-it-yourselfer, not a bad option. BTW, you may NOT want to breathe the fumes!
Another option for 'hot-cold bluing' is to heat up the part either under a torch as previously suggested, or even under HOT running water, and also nuke a cap-ful of cold-blue in the good ole' microwave. Believe it or not, you then end up with hot metal and hot solution, which works well for us 'home-folks'. HTH.
Are you saying that 320 as a maximum finish as in, "no lower grit than 320"? Or that it does not work well with highly polished metal? Does it usually require more than one application? Or is one just fine? Thanks.