Painting steel

[armedandsafe]

I would like to paint my cut/guide caps, which are plain steel, unplated, polished 7/8" nuts. I am reluctant to use spray cans because they are so wasteful and hard to control. I'd like to use my air brush set up, but I'm reluctant to pay $15 per ounce for the paint, as advertised during a search for airbrush paints.

I am aware that one should prep to absolutly clean, and that primer is recommended. I want a thin, tough coat. These items never see anything but fingers, so chipping and scuffing is not a problem.

Any suggestions of materials for priming, painting and thinning would be appreciated. We have the usual big-box stores, hardware stores and one Sherwin Williams store in this little burg.

Thank you.

Pops

[lakeside53]

Don't give up on spray cans. I use Rustoleum Professional and get great results. Paint with their primer, and a few minutes later (while primer is "tacky") a top coat. Another top coat in 15-20 minutes and you're done. Very soft for 24-48 hours, but it will get there.

The new rustoleum pro cans do not clean when inverted so take off the tops after use and soak/claam in laquer thinner.


and.. I have a HVLP and an airbrush sytem - way too much work to setup and clean for small jobs.

[flathead4]

...but I'm reluctant to pay $15 per ounce for the paint

I've shot Tractor Supply enamel and craft store acrylics through my Badger airbrush with great success. I've used the Testors model paint, too. Just thin until you get the results you want. The only "airbrush paint" I have ever bought was with a 30 percent off coupon at the Michael's.

On the other hand, if you just want to black them, you could get one of the metal blackening kits from a place like Eastwood. I have a kit I bought about 20 years ago and still use it for the odd bolt or nut. I also used the kit to blacken home made hooks for a pot rack I made for the kitchen.

Tom

[armedandsafe]

I think I should expand on this. A production run is 50 units. That is 100 nuts. I'll be doing a production run once a month. The volume therefore is enough to justify the setup and after clean time.

I'll do some research on the metal blackening you mentioned. I have tried bluing them, but the results aren't to my liking and I don't have a hot blue can.

Pops

[914Wilhelm]

Get one of the cheapo HF powder coat guns, some Eastwood powder and a free discard oven. You'll get a tough finish in less than an hour.

[Mike Folks]

Get the parts throughly clean, spray on several thin coats, and then if your wife/girlfriend is agreeable, open the kitchen windows and bake the parts at 300 F for about an hour.

The paint will outgas, but after cooling down, it wil have a durable finish. I use this method for metal motorcycle parts. It's really tough, and paint stripper has difficulty removing it.

[lakeside53]

Take care with 300F.. make sure the paint can handle it. Some is only 200F. A cardboard box and a ceramic heater can suffice.

If you really want to bake it, find some true baking enamel and follow the manfs recommended temperatures.

100 nuts will take a minute or two total to spray each coat, at most

[Deus Machina]

Get the parts throughly clean, spray on several thin coats, and then if your wife/girlfriend is agreeable, open the kitchen windows and bake the parts at 300 F for about an hour.

The paint will outgas, but after cooling down, it wil have a durable finish. I use this method for metal motorcycle parts. It's really tough, and paint stripper has difficulty removing it.

I've used this method on quite a lot of things.
I use Rustoleum's Professional line, and limit it to 240 degrees or so.

I've done paintball markers that don't show a scratch after me sliding around with them.

I do believe Rustoleum sells their Professional paint in smallish cans now, if you prefer to airbrush it. Just thin it appropriately.

[firbikrhd1]

Being wholly uneducated in airbrushing I have to say that years ago (1977) I had a Dodge van with a scratch in it's new paint. Not knowing better I bought a quart of the correct paint for the vehicle, thinned it and used an air brush to touch up the scratch. When finished you couldn't find the scratch, the paint lasted well until about 1984 or so when someone hit the van in the back and I had the whole thing painted. The air brush wasn't any worse for the wear after using regular automotive paint in it either.
So, maybe airbrush specific paint isn't necessary?

[PaulT]

I've tried most of the "cold black" systems and haven't had any success with them, in terms of getting a finish that's anywhere close to the appearance and durability of real black oxide.

If you search "cold black" on the Practical Machinist forum you'll see some discussion of these systems.

Krylon spray bombs and a bake at 200 degrees (we have a toaster oven dedicated in the shop for this purpose) is what we do now for small runs of small parts, for larger runs we have a real black oxide put on them.

We made our own spray booth for these spray jobs, basically just a big plywood box with a false back that holds furnace filters, a blower mounted on the true back sucks air through it and vents it out through a large (12") hose vented outside the shop. If you search on spray booths you'll see some examples of what I'm talking about.

Paul T.
www.power-t.com