mapleleafs-13 

I wanted to do a bare metal frame bike project to be geared.

This is mainly because I picked up a frame that has really bad paint and I'm thinking about just getting it stripped or sandblasted.

After I have removed the paint what would you recommend for the bare metal finish? A few coats of clear coat? Is there anything I should do before applying?

Also would you recommend sand blasting or getting it chemically stripped?

It is just you typical steel frame.

unworthy1

if you don't care about rust go ahead and clear coat...rust will eventually bloom under the clear, and spread.
If you want better, get it blasted and immediately clear powder coated, no moisture and especially no handling between the blast booth and the powder rack.

sloar 

chemical strip will leave the metal smooth and shiny, unless there is rust spots. sandblasting will leave the metal rough. what i would do is blast it then sand it moving up to finer paper until you get the finish you want. a cheap way would to just use an enamel clear, a great way would be a clear powdercoat. i did a trek aluminum mtb and i rough sanded the frame leaving swirled sanding marks, then cleared over it. its held up really nice.

20grit

Powder coating is porous. Why would that be the recommendation over a liquid in an effort to prevent rust?

sloar 

hard to see chips in clear over bare metal, you wont notice it until rust pops up, then gets under the rest of the clear. powdercoating is more durable. if done right i wouldnt think it would rust. i could be wrong though. i'm not really into powdercoating.

unworthy1

nothing is impervious, but powder coating is usually a much less porous film (since it's usually thick and a very evenly applied plastic resin) than most liquid paint.
The thing that goes in its favor is that most powder coaters will get the thing blasted to bare metal, dusted and baked without ever touching it with bare hands and before ambient moisture can attach.
I have sprayed a fair bit of bare steel (with high quality paint in a spray booth as well as rattle cans) and despite how careful I have been (not always) I have yet to see one that doesn't eventually rust under the clear paint.
What examples I have seen of clear powder coating have shown no (or very little) rust SO FAR.
as always, YRMV...and some folks like rust, or at least don't care.

Bianchigirll 

I think the idea of doing this has vexed steel fans for a long time, or atleast since Gita used a bare DeRosa in a ad in the late '80s. I would love to do it to Hilda one day.

sloar 

here is my bare aluminum trek..

rfj

Check out everbrite protectaclear. https://www.everbritecoatings.com/car...&products_id=5

unworthy1

I have used Everbrite ^ in the past and I like it for some uses.
The seller is pretty close-mouthed about what's in it, but the MSDS seems to indicate a nylon resin.
The upside is you can get smooth results with a variety of applicators (brush, sponge, even a cloth pad) cause it self-levels, downside is it's pretty fume-y and you are required to use nitrile gloves, and a respirator if spraying it, which tells me the solvent is toxic.
Never tried it (yet) over bare steel.

ColonelJLloyd 

BF member DRietz had his Soma Smoothie PC'd clear. It'd be nice to have an update to the thread. It was pretty cool.

no_safe_HAVEN

Considering this same thing myself. Have a unknown 531 frame that Im going to build up. It has a sweet Gunmetal grey patina to it and I wanted to keep the look and add some color accents to the seat and head tube. And out line the lugs. As there is no heritage left to the frame Im going to have some resto-mod fun with it.


The third school of thought about a bare frame is using a clear rust inhibitor from the hot rod world. Like this one. On a couple rodder sites I follow a lot of guys give it praise.

Or there is also POR15 that comes in clear... Never used it though. Dont know how "clear" it really is.

For me Im going to shoot on a clear adhesion promoter followed by 3-4 coats of quality automotive urethane clear. And just be really diligent about checking for chips.

Bianchigirll 

I know the idea of bluing has been discussed but I wonder if a frame could be case hardened or would the heat be harmful to the brazing?

https://en.wikipedia.org/wiki/Case_hardening

thenomad

I took a rotary brass brush to a frame, cleaned it all up and hit it with simple rustoleum clear enamel. Looked great and I figured it'd be easy to touch up and redo if needed. A buddy has it, over a year and a half now so maybe I should take a look at it.

theblackbullet

I wish I had pictures of it, but a few months ago I received a steel track frame in a trade that was bare steel. to prevent rust, the previous owner rubbed used motor oil on the frame. It didn't rub off so much that touching it would get you filthy and the finish looked really cool!

mapleleafs-13 

i was trying to keep the budget low. did the rustoleum hold up really well?

is there a normal clear coat i can buy from the store or should i go with the rustoleum?

HeyPip

Case hardening will make the tubing brittle and cause it to crack. Plus, it will distort the frame hugely and cause induced stress and potentially cracks. The frame would crack if you tried to straighten it. I doubt that much of the brass in the joints would be left after case hardening. Case hardening is usually used to put a hard surface 0.005" on a low carbon steel, in thick sections. It gives a hard bearing surface on, for example, shafts, but leaves a soft chewy and crack resistant (low carbon steel) core. Cheap BB and pedal spindles were case hardened low carbon steel, back in the day, but Campagnolo used alloy steel with nickle and chromium so they were through hardened and tempered.

Pip

gingi310

Here is my Bianchi Grizzly frame which I stripped and had clear powdercoated



More Pics: https://www.smugmug.com/gallery/29830063_439Pgh

mapleleafs-13 

How much was clear powdercoat

Bianchigirll 

I think depending on your location $80 to 130 or so

Ex Pres 

There are also clear primers / adhesion promoters. Whether they help deter rust as well I have no idea.
(spray can - Duplicolor CP199)

I see Rust-Oleum makes one, too. No. 251572 (stupid hash tags won't let you use a number symbol any more).

simmonsgc

Yep. Below is a Trek that had the paint falling off in sheets, so I sand blasted it in a buddy's booth. I was thinking how ugly it would be in this rough texture under a clear coat. Sloar is exactly right; if you blast, sand by hand until you get the level of "reflection" you want. Unless you like that "foggy, rough" sandblasted finish....to each his own, of course.