Standalone 

I'm into cheap '80s bikes. I can appreciate all the wall hangers and all the museum worthy bikes that either hang on walls or get out there for regular use. Never owned a bicycle worth more than $350, though. Maybe my old Burley tandems.

The only mentions I've seen here on C&V of spray paint are pretty derisive.

I just sanded the bubbling on a $75 '83 (correction, 84) Trek 620 frame, taped it off, and hit it with some shiny Krylon primer. Nothing was badly pitted; things look solid. Now the sparkly pewter DuPont Imron paint bike looks like it has aluminum foil stickers here and there. It got some framesaver when I first bought it, but not a dip in Oxalic.

Basically I want to see how I like touring with Biopace & Bar-Ends and compare it to my half-step+granny/DT set-up on my other tourer.

I'm surprised that I don't see more talk of this kind of stopgap rust remediation. Am I ruining or saving the frame? Or maybe not really making a difference in the longevity of the frame?

himespau 

Pictures?

RPK79

+1

This thread is pointless without pictures.

SJX426 

If done well, saving. Stopping rust will save the frame where treated. The problem is where you don't see it. Speaking of Burley's, here is a Burley frame where some of the rust was not visable under the paint:


BTW, that 20 is worth saving. I am doing a repaint of a 610:

Ex Pres 

If you've eliminated the rust and resealed the area with your paint, then you're helping preserve the frame. Now the cosmetics? You're the one riding it.
But primer, if left bare, is:
1. not the best surface barrier, and
2: intended for a top coat to stick to it, so road grime, etc. will stick to the primer better than to a proper top coat.

rhm

Can't address your question, but just want to offer a big thumbs up for a great thread title.

Standalone 

I think my Rhumba probably looks like this under the paint. There is surface rust within the frame and the checking in the decals shows age and exposure. I picked it up for $200.

#2 is an interesting point.

ultraman6970

"I just sanded the bubbling on a $75 '83 Trek 620 frame, taped it off, and hit it with some shiny Krylon primer. Nothing was badly pitted; things look solid. Now the sparkly pewter DuPont Imron paint bike looks like it has aluminum foil stickers here and there."

The problem you have is that krylon painting just SUCKS, even their primers sucks and thats the problem you got. You needed to seal the what's under the primer. What you do is to put the primer, then use another primer sealer or another color, maybe a white over the primer and then paint with the imron.

IMO what you should have done is to just discard the Krylon crap and have gone all the way to bare metal and then applied some acrylic primer and then the imron. Another solution w/o going to bare metal is primer, then acrylic primer to seal it and then the base color.

IMO everything started bad at the moment you mentioned Krylon. Don't use Krylon clear coat to go over the Imron because probably the imron will melt and might start bubbling then you have to start all over again.

Now you have two options, go bare metal and please dont use krylon no more (or any other home depot primer crap like rustoleum, even the car rustoleum one is crap), go bare metal ans start again, second option, sand to even the surface and put a primer sealer, then white or maybe light grey imron to seal all the crap behind it and then paint your pewter, the problem with this solution is that you will end up like with 30 coats of paint.

Good luck with this one, now you know why bicycle painting is so expensive A lot of work.

Standalone 

you can see above that I missed a little of the bubbling on the lug.


The thread is now useful.

Standalone 

Really? For a rusty $75 bicycle?

What exactly makes this paint "Crap?"

This is the derision that I'm talking about in C&V. Some folks may have time and money for this, but not me. I want to tinker a bit and ride.

I don't think I've done anything lastingly bad to the bike. As you say, it needs a repaint. This is not happening anytime soon, and I would disagree that there are only "two" options.

fietsbob

Strip to bare steel primer and top coat . air dry paint is what it is. at least the touch up
will be as easy to do as the top coat was ..

Catalyzed Pro Paint-jobs and powdercoat is not so simple to touch up,

you end up using Air dry Paint for that as well .


Fond memories of my black Primer, transparent green topcoat, paint job
I did on my bike build.. I did , when JFK was still Breathing ..

Standalone 

Next step is to put my Grateful Dead stickers on it.

orangeology

love the title of the thread.
as grew up with rattle cans—pls don't ask—with a little experience on bike frames, tho.

Rustoleum primer 'crap' is ok, after all. it seems sealing and priming well,
with self-claiming light-rust-cure that has no way to prove however.
it actually stick to the lightly rusted or sanded bare metal surface pretty well.

the problem is how the primer works with the next, 1st paint coat over.
'Regular' auto-body rattle can including engine block ceramic stuff DON'T ADHERE to RUSTOLEUM PRIMER WELL
—even after a careful wet sanding.
it looks fine in the beginning, then start to 'catalyse' together a bit when the clear coats are given
—with either one-part regular or two-parts clear coat stuffs.

when attacked, it peels off all together with no hesitation leaving nice clean surface of the white primer.
like they've never stuck together. literally looking like there was air layer inbetween the primer and the next coats.

but again, as you've said. bearable with a cheap rusty $75 frame i guess.
personally, i like all the patinas on vintage bikes. bit of peeloffs, scratches, rusty bubbles, torn decals etc.

my bigger growing interest is more like 'preservation/conservation' it with proper protection from further damages,
not like stripping all the way and repainting it if possible.

Kobe 

You'll have to add a few inches to the Trek to make it the size of Bill's, but I like the Grateful Dead theme.

Leave the silver Krylon and just ride it.

ultraman6970

You are asking what could have happened. Im not the 1st to tell you that you needed to seal the paint 1st.

Dunno man, if you want to continue using krylon is your money and your time too

Clearly you sanded and put some krylon and then you put the imron and you got that chroming color? interesting To me that imron doesnt even look like pewter, my best guess is that you got the wrong color because pewter is not that silverish.

Paint something else, a piece of plastic or metal w/o primer and see how it turns, if it turns silver you got the wrong paint or you did not mixed the paint too well, or you got a separation of pigments or something.

Go to bare metal and then paint, you will waste more time painting over it again.

Use U-pol primer next time, that will hold better than krylon because was made to repair cars.

Good luck.

Standalone 

Ultraman.

Trek Bikes of the era were imron, as I understand it. The Pewter is the '83 catalog color. What you are looking at is raw Krylon primer. From a can that I have had around forever. No top coat.

If I love the way the bike rides, then I will be able to post in the "post your orange powedercoated trek bikes in your Park Tool workstand.... It will be worth the investment.

If not, I'll keep it running and my son will be riding on it in about five years. Hopefully touring with me if my knee is any good.

himespau 

At that point, why bother taping it off and not just pull the headbadge and do the whole bike? I'm in the midst of doing a (very crappy) wet painting of a bike (well, 2 and I'm about to restart after a 18 month "break" - aka giving up) and it looks like spray priming would have been faster/easier. Maybe next time.

Standalone 

Yes. But with a doctoral application to complete, five classes to teach, one class to take, a department to co-chair, my 4th Gup Karate test, etc., etc.....

This took me about three hours of work all told. Bike has only done 20 miles since I installed the headset and BB. A teardown seemed overkill. Maybe in a few years. The rattle can patches can hopefully hold the bike together until then.

himespau 

I completely understand. Maybe next time I'll have to try your spray approach. Sure looks a lot smoother than my brushing it on (no matter the brush, I always end up with stroke marks to sand down).

Ex Pres 

And if I'm not mistaken the decal set and canti studs make that one an '84 model, not an '83.

jj1091

Just curious on your advice for paint types. I almost never repaint a frame, just do some touchups. On the few I've repainted, I use automotive paints like Duplicolor, acrylic lacquer. Any advice about this type of paint? So far, I've not ever tried to put on a topcoat, just use numerous coats, then a polishing compound, then wax.

Standalone 

Yes. You're right of course. The '83 had no studs and the wraparound stickers. Brain fart. My 520 is the '83. In my defense, this 620 was sold to me as the more desirable '85.... :/

The '83 Catalog with it slanty writing is the coolest, though.

Standalone 

+1

I was hoping to scare up some empirical facts about home-accessible paint solutions. I haven't done a lot of searching on here about it, but haven't seen a lot about paint. Maybe those aren't the threads I tend to click on....

jj1091

That's me, also. I like the battle scars, I touch them up with a brush, finding paint as close to the original as possible, then doing a little mixing in a cup with some colors to get it right. I've gotten into a bit of repainting the original graphics, getting better at it. I'm an artist, anyway, do landscape painting, so the mixing thing if fairly easy for me. It's easier this way, to me, to preserve the original decals, stickers, and graphics, than it is to mask off everything. The masking just never seems to come off cleanly and I end up touching up the edges. Touching up, then polishing the old paint leaves some fairly good results.

ultraman6970

This is the deal with paints ok?? Not that I paint cars ok? not that I paint bikes professionally because I dont, just paint as a hobby and have learn some stuff while learning, like what to mix and what not... what works and what not.

For cars in general you have like 2 types of paint (making this thing as simple as possible ok because can get complicated), there are some of paints that are called hot (lacquers like rustoleum and pretty much all of the rattle can around, and some of the hobby paints that goes over plastic models), then you have cold paints like polyurethane, some people talks about porous and non porous paints that is basically the same thing...lacquer is not porous and car polyurethane is porous paint. In paints you have water based paint (tamiya for example) and oil based (duplicolor car line is like an oil based paint, bad stuff it paints like if it was latex for walls) and polyurethane that i like a solvent based paint. Telling you all of this so you guys pick the right stuff...

The biggest difference between rustoleum lacquer and the duplicolor car line is that they dry and cure by air, thats why when you paint a bike with those paints the crap after a week is not dry and sticky as hell. They need to have a really good temperature and basically the ideal conditions to dry, by the way takes like 6 months for that crap to cure. The results generally speaking arent that bad but the issue is that probably after like a year or less the paint start cracking off the frame with only giving it a nasty look. No wonder is cheap too, remember this is not a porous paint too, that means that whatever is under wont be able to breath, it seals what ever is under it.

Polyurethane and car paints in general are dried chemically, besides the air you have to add additives (activator is called) to the paint to dry even if cold or if its hot. That's the reason why if you paint with this next day you will be able to put the bike together w/o any problem even if you put the frame to dry in a super cold shed. This paints are purous, that's why you can shoot them virtually over any other type of paint and you won't get problems of bubbling (but you never know what could happen tho), they stick really well and level really good.

For example if you paint polyurethane over lacquer almost sure nothing will happen becaue polyurethane will let the lacquer to breath, if you paint lacquer over polyurethane the bubbles and the melting you will get will be just awefull. So as a rule to play safe never mix them.

My best guess is that duplicolor touch up paint is water based and thats why car paint doesnt react to it, was an acrilic lacquer like hmmm.., the hobby line of "house of kolor" I would not even dare to use it over car paint because will soft it and melt it down to the darn metal (did a test once and had to repaint a fork due to the experiment). Tamiya hobby paint in jars is water base, pretty much neutral, you can use alcohol to thin it, it will evaporate faster than water that means faster dry times.

Clear coats, no rattle can from rustoleum or duplicolor will match even the cheapest polyurethane car clear coat in the market, starting by the UV protection and finishing with the shine you will get. Generally speaking HD clear will start getting yellow after a few months because of the UV protection, if you notice a couple of years ago they started putting UV protection in their labels. If you go to a car paint shop you can find "2K clear coat" in a can, that's the stuff cars have.

Primers, bicycle industry uses a primer that covers almost everything, is an acrylic type of primer that will cover any imperfection over the surface of the frame, really durable and expensive aswell. In primers nothing from HD will last as long as car primers aswell, if i had to recommend a primer I would recommend u-pol high built primer, that one comes in a can almost double the size of the rustoleum, comes in different colors aswell, this primer is for car industry use so you know that you are using good stuff. If you are painting aluminum you need a special type of primer that sticks and etchs over the surface, for carbon fiber I would try to find some primer that works with plastic (u-pol has them all).

Working with decals I never had a single problem using polyurethane clear, the thing let the decal to breath so it wont dry and crack that is what usually happens.

Paint brands, basically everything is the same thing but you always have to ask if you can mix one brand with another because not all the time you can do it. So my advice is to stick with one brand and avoid mixing stuff because sucks to restart the whole job due to an experiment went wrong. If a place refuse to sell you half a pint of paint ( enough for 1 bike or 2), go somewhere else. The other thing is that with some brands the only size they sell are half gallons or full gallons.

Ingenuity is the key IMO, there are zillions of brands and paints around and there is no way to know what could work and what not, for example from the rattle cans you have lines of paint for grafitty that have awesome colors, my problem with them is that I haven't use them so dunno what type of paint is and even if you call them asking they will say... "is acrylic!" ok... everything is acrylic, duh..! so if you dont try you wont know. Just do a test in a plastic tube and see how it goes, but in the only thing I would not trade the type of paint is in the clear, nothing is better than car clear coat.

Hope this helps, too long eh