Hot oil bluing. Need some advice please.

[.50cal packer]

I have a rifle project that I'm working on and need all the advice I can get. I've done some research on hot oil bluing, but there seems to be gaps in all the things I've read. First- I know that with any bluing, the pieces need to be brought down to complete bare metal, with 0 oil or contaminants present. I've seen this done, cheaply, with hot white vinegar. But I also know that when doing an action and barrel together, you don't want the vinegar to get into the barrel. How do I prevent that, or is there another way of getting the bluing off in an easier fashion? I'm doing an entire gun, so all hardware will be included in this process and the vinegar is cheaper by the gallon by comparison to ounces of bluing and rust remover. Second- I'm aware of heating the metal up to the point of changing it's color, but not bright red to the point of weakening the metal. Third- I slowly drop the pieces into the oil and let sit overnight or as long as I'd like to get the desired color. The problem is, they never mention what type of oil is best suited for the procedure. I'm aware it is motor oil, but is it used or is it new. Is it regular, durablend or synthetic; and what is the weight of the oil used? I've heard of using stump remover to do this as well, but I feel that it would be impossible for me to keep every bit of moisture out. So that method is out of the question. I know about Oxpho-blue, dura-kote and even looked into wonder blue. I haven't heard of any completely happy bluing stories with these and ultimately, they end up rusting quickly. So I'd like to try this. Please help. Any and all advice is welcome, and if you respond please be as specific as possible.

[Doyle]

For the barrel plug, I've heard of using a slightly tapered wooden dowel tapped firmly into the barrel. When immersed in water, the wood will swell further sealing the grooves. When you are done, let the wood dry out to shrink then drill a small hole into it and insert a screw to pull it out.

[.50cal packer]

Awesome advice Doyle about the barrel plug. Simple enough to do. Now I just need some info on the oil, and I'll be set. Thanks for the help.

[Jim Watson]

One example I found said to use conventional motor oil of a cheap brand.
Be aware that you are actually heat bluing the metal which is around 570F. This is into the draw temperature range for some steels.

[.50cal packer]

Jim, what you're saying, is I'm heating the metal so hot, that it reduces the tensile strength and could actually stretch/contort the barrel?

[jaguarxk120]

Heat bluing should not be used for ALL gun parts.

At those temperatures, the heat is actually drwing or changing any heat treatment there was in the part to start with.

[.50cal packer]

I have a Mosin type 53. It was drenched in cosmoline, so as always, I do my overnight soak in Mineral Spirits to soften and melt away as much as possible on all the metal parts that aren't on the stock. Bluing wasn't great to start with, but after the bath in the m.s. the majority of the bluing came off. I've always liked the way the oil bluing looked. The method seemed easy enough. I have read, not heard, all sorts of mixed reviews on just about every cold bluing application out there. The only part of the metal not blued is the bolt. Which I never intended to do in the first place. So, If you're saying don't' do it, Then what recommendations do you have?

[mapsjanhere]

You don't want springs, sears, lug bolts etc to go through the hot oil process. There is a reason why typically only the receiver, barrel and trigger guard are treated. I would also recommend a decent infrared thermometer to keep track of the temperature of your piece - too hot and you can damage the gun and set your oil on fire.

[James K]

I do not recommend the hot oil or "oil blackening" process, and I think the OP has a very poor understanding of what is involved. Oil blackening was used extensively at one time by Springfield Armory for Krag and early M1903 receivers. It produces a nice black color, but was done as part of the heat treatment process and could never be re-done (receivers that had to be reblued were rust blued).

Heat bluing of small parts is common, also usually a by-product of heat treatment (Luger ejectors and safeties for example, which were made a straw color, or Krag extractors, which came out a lovely blue.)

Both types of bluing require heating the part to a level that can draw the temper and leave the part soft or, conversely, brittle; either would be dangerous in something like a rifle receiver.

The assessment of the various "cold blue" treatments is correct; none will give a good and durable blue. The only two methods that will are hot salt bluing, which I don't recommend for home use, and rust bluing, which gives good results but does require a means of heating (boiling) the barreled action.

Today, there is another alternative, which is very DIY friendly - paint. There are a number of coatings on the market (check with Brownells) which are easy to apply, durable, and can be had in various colors to duplicate bluing or Parkerizing if desired.

BTW, you don't put a wood plug in the barrel and then use a screw to take it out, you use plugs that are long enough to stick out both ends so you can use them to handle the action without getting burned or leaving fingerprints.

Jim

[.50cal packer]

Jim, you must be correct about me not knowing anything about oil bluing. Hints the original questions. At most, I've seen a handful of videos and read as many stories about hot oil bluing on firearms on the internet as I could find. Trust me, there isn't many out there. I'm assuming though, without checking first, the paint you're referring to is perhaps, similar to a dura-kote or a gun-kote? Applied with an airbrush or a reasonable facsimile thereof, then heated on a low temp? If so, that would be a significant decrease in all safety aspects. It would be at most, closer to something I could manage, without setting myself on fire, or blowing things up and hurting others. I didn't realize that either Kote's made a paint or finish that wasn't a pseudo parkerized look. If they make a deep blackish blue, that is truly glossy, I'll buy by the gallon. As always, Thanks for the help and suggestion.

[Jim Watson]

Most of the paints recommend that the surface be grit blasted.
And, as with any metal finish, it must be completely degreased.
Applying and baking the paint is probably the simplest part of the job.

[Dfariswheel]

Some of the better gun coatings like Lauer Duracoat are air curing. They don't need to be baked.
It just needs to be left untouched for a few days until it hardens, and it doesn't reach full 100% hardness for as much as three weeks.
It's a two part mix, but does come in a one part, and needs to be sprayed.

Duracoat comes in MANY colors and in semi-gloss colors and I think gloss colors.

http://www.lauerweaponry.com/

[4V50 Gary]

You might want to research Express Bluing. You need a propane torch and a tank long enough to hold your workpiece.

[guncrank]

Duracoat has a gun blue color that match regular hot blue color pretty close

[Old Stony]

I have done a hot oil blue to match parts such as buttplates on old Winchesters that were so far gone that something had to be done. I wouldn't recommend this for any parts of an action though because of the heat involved. You might consider a Belgian Blue , as it is fairly easy, and you can do it at home in your garage, using only a camp stove for heat. I have done things such as rolling blocks this way and I was very pleased with the results. You just need a couple of metal tanks for the bluing and rinse. Brownells sells everything you will need, and it will produce a nice deep finish something like you might have seen on vintage guns. The more coats you use, the darker it gets. The surface can be prepped using only garnet paper in fine grits. The aluminum oxide papers can leave an aluminum residue in places where they will cause spots.

[4V50 Gary]

Old Stony is suggesting the same thing I did


1) polish the barrel
2) degrease with acetone
3) mount the barrel such that you can rotate it. A piece of brass inserted into the barrel, with one end of the brass slipped into a pipe that is secured in a vise. This allows you to remove the barrel without touching it via the brass rod.
4) propane torch. Heat to 200-225f
5) use cotton swap to apply Belgian blue evenly
6) apply torch
7) immerse in boiling water for 5 min
8) card with oil free wire brush
9) repeat steps 4-8 3x.
10) don't touch. apply oil. Let it cure for 24 hrs.

[guncrank]

Express Bluing was a brand name for a Mark Lee rust blue product.
Express
Rust
Belgium

All the same name for the process
Not that it matters any

[guncrank]

Originally Posted by Old Stony

I have done a hot oil blue to match parts such as buttplates on old Winchesters that were so far gone that something had to be done. I wouldn't recommend this for any parts of an action though because of the heat involved. You might consider a Belgian Blue , as it is fairly easy, and you can do it at home in your garage, using only a camp stove for heat. I have done things such as rolling blocks this way and I was very pleased with the results. You just need a couple of metal tanks for the bluing and rinse. Brownells sells everything you will need, and it will produce a nice deep finish something like you might have seen on vintage guns. The more coats you use, the darker it gets. The surface can be prepped using only garnet paper in fine grits. The aluminum oxide papers can leave an aluminum residue in places where they will cause spots.

Hummm garnet paper
Interesting
So that is those spots.
Thanks OS
Will try that

[guncrank]

Brass rod is a good trick
Will keep that in mind