hokiefyd 

By "soft paint", I mean it's so soft that you can pretty easily leave a small but permanent indent with your fingernail. This is what I'm pretty sure is original paint on my Trek 750 and it wipes down with soap and water just fine. But I'd like to go further, with polish and/or rubbing compound. Additionally, I'd like to apply some touch-up in some areas and try to buff/blend/match afterward. I'm certain that the potential is there to damage the paint with even minor abrasives, because of how soft it is.

Have you had a bike with paint as soft as what I'm describing, and what'd you do to bring it up?

jdawginsc 

Repaint, and thin no more.

Ive had good success with T-cut and mothers. And I have only had to repaint half of the time (kidding about that).

Im surprised since Trek paint is usually pretty durable in my experience.

Wildwood 

It's only original once. I approach refinish decisions slowly.
Wash, treat any rust, wax a small section to see how the paint polishes. If it isn't as bright as you like try a 'mild cleaner polish' (on a different section) without much pressure, then wax. Rubbing compound comes next. Doing the frame this way is no small task, get some small brushes and clean cloths for the job. How many components are you wanting to remove?

When you've got what you want with the frame paint then look for your touch-up. I will let more qualified people describe feathering the sections with new matching paint. For small chips a q-tip often beats a tiny brush. Wax, wax, wax.
Ride, ride, ride. That's really all that matters.

edit: Check out the Before and After thread in C&V - shows examples of repaint and polishing magic.

Bad Lag

Soft paint is almost certainly rattle can paint.

It is almost certainly NOT original paint unless it has been exposed to some sort of chemical vapors or other damage.

Try baking the frame. Make an oven using rigid foam insulation from the hardware store and aluminum duct tape. Put a heater inside and your frame. Bake for 24 hours at 100 deg C.

If that doesn't fix it, nothing will. Rattle can paint does go bad (has a shelf life). If it wasn't properly mixed (shake the can and rattle the ball), it could be bad, too.

Doug Fattic 

I'm a painter. It is possible that at the factory they didn't get enough activator into the paint before they sprayed. That is a very easy mistake to make. Imron used to have a 3 to 1 ratio before it became 6 to 1. Or they may have thought they were adding activator but used reducer instead. Or they may have taken a break and thought they added the activator before the break but didn't.

My recommendation is to do what Bad Lag suggested and heat the frame up. Putting it into a parked car in the sun for a few hours is what I would try 1st. That requires little effort and will lead to the best results.

RiddleOfSteel

Remind your paint of Rule #5...

hokiefyd 

I appreciate all the responses. I bought the bike from an older gent who claimed to be the original owner and he didn't seem like the type who would have resprayed it. The drive side chain stay has the original (and crackled) clear film protector still applied. The decals appear to be all original. You can "feel" them, but they may be under a very thin clear coat. I have sprayed a frame before, and this seems even softer than that. It feels almost like a very thin thermoplastic vs. paint.

Perhaps it has been exposed to some sort of environmental condition that degraded the finish. I will say that, despite its relatively good appearance on the outside, I found a lot of red-dust-rust inside the tubes when I took the bottom bracket out shortly after I bought it. I don't know if that may be indicative of some sort of environmental damage. It does look "cloudy" in some areas, but it doesn't seem patchy or splotchy -- whatever happened to the paint, whether it was an external factor or an improper mix from the factory, seems to be relatively consistent across the paint.

And it's that slight cloudiness that I'm trying to bring up on it, if I can. I am not interested in re-painting or powdercoating. If my chances of good results are 50/50, then I'll probably leave it alone.

RustyJames 

Doug Fattic Would paint remain soft after 30 years? I would think that if it isn’t cured by now it won’t ever cure. If the frame has recently been wiped down with a solvent that would explain the soft paint.

jdawginsc 

That is a great idea. Would that also help with rattle can paint?

Doug Fattic 

The kind of paint Trek used years ago was a polyurethane paint. It is like epoxy that hardens by chemical action when an activator is mixed with the paint. It has to be sprayed within a certain time window after the activator is added otherwise it will turn into a solid mass in the mixing cup. Often a reducer is a also added to the mix to make it flow better. Sometimes an accelerator is the 4th additive. All of these ingredients have to be mixed in the right ratios or the paint won't harden properly. In other words it will remain soft - exactly like the OP described. Eventually all the solvents in the paint evaporate so the paint isn't still "wet" but neither is it totally solid.

There are times when I've had to wipe down a painted frame with lacquer thinner to remove rattle can paint or something else that shouldn't be there. Sometimes it had to be really soaked to get everything off. It temporarily can soften the bark of the paint a bit but that doesn't last long. It is unlikely that there is any other reason (although anything is possible) for soft paint other than it wasn't mixed properly when it was sprayed. It is easy not get the ratios right.

guy153

You could put rattle can 2k clearcoat on top. This also has a catalyst (you pop a pin in the bottom of the can and then it's good for 48h). It sets actually pretty hard.

RiddleOfSteel

Yup, just gotta wear proper gear when you do it--2k clear is pretty nasty, but it does the job well!

guy153

I use it outdoors and with a respirator. Yes it's pretty good. I was doing some tests the other day on some tubing I had with it on (long story, I was modifying a frame to add more standover height, so the old painted TT has now been donated to science). I tried bashing it with a steel tube comparing with an old powder-coated chainstay I have from a Trek frame I have that failed. The powder coat is definitely tougher (it's incredible that stuff), but the 2k clear coated tube was only becoming damaged at the point that the tube was actually getting small dents in it. In scientific terms I was whacking it somewhere between "pretty hard" and "really quite hard" before it was coming off. A coating with spray.bike really just needs a somewhat mild tap before it starts coming off.

The acid test is whether it can survive sandblasting with stones and mud from winter riding (spray.bike can't). I've only used it so far on bikes that have fenders anyway (and they're fine).

And I don't know how much of a problem it is if the paint underneath it is still soft. I use regular acrylic paint under the 2k and leave it like a week indoors to absolutely completely dry out because one the 2k is on it's all going to be sealed in. Whether this is a problem depends on how flexible the 2k is.

When buying the stuff also make sure you get the gloss one if that's what you want (there's a gloss, a satin and maybe a matt). The gloss actually looks really good.

hokiefyd 

This 2K Clear Coat from SprayMax -- this is the stuff you guys are talking about? I've never heard of it, but it looks interesting. I appreciate the use tips.

https://www.spraymax.com/en/products...2k-clear-coat/

guy153

Yes that's the stuff. That one with 36E on the can is "satin". You want the 88E for full lush glossiness. It's quite pricey but works. One thing to watch out for is give it at least 48h before building the bike back up, ideally longer (or just be careful) to let it reach full hardness.

Doug Fattic 

I've never used SprayMax myself because I have professional equipment. Their rattle cans can be loaded with the same paint I use (primers and color coats - not just clears). The SprayMax clears are polyurethane enamels (or urethane enamel) that have to be activated with a separate activator so the paint chemically hardens. Most paints hardens because the solvents in the paint that allow it to flow out evaporate. Heating just speeds up the process. Just to be clear SparyMax cans have a button you push on the bottom of the can that then mixes the activator with the paint. If you don't use it within a certain time period it will harden solid in the can.

If I was going to paint a frame without all my pro equipment, I would use SparyMax primers too. These are also catalyzed paint like epoxy. This gives a good foundation for the color coats and clears that go on top. As I understand it, Automotive paint stores can fill almost any kind of paint they carry in stock into SprayMax cans.

Mr. 66

I haven't used the 2k clear coat, but I have used the primer and black paints, both worked out great. I did etch the frame immediately before applying the primer. I don't know if it helped but it didn't hurt the process.

hokiefyd 

I appreciate the suggestions on the 2x clear coat, and I also appreciate and respect the thought that it's original only once, and it's original only until it's not. I do have another (and not valuable) bike frame in my stable that I do intend to rattle can this season. It's already been spray bombed and I have a pretty classy combination of colors that I'd like to use on it...I believe I may try the 2x clear on that frame and, based on my results and experience from that, only then consider to attempt some improvement on this Trek.