ramseykp

So i didn't "build" a frame but i do have a bunch of parts im going to throw on a Cadd3 CanOale frame. but its paint has been removed by the guy who sold it to me. So, I need to paint this bike and I have no idea how, or where to even start researching how. I know I could get it done for 200 bucks but don't want to spend that much money. I just want to protect the frame from rust and such. If i could, I would just leave it unpainted but I know thats bad for aluminium. any suggestions as to what I should do?

squirtdad

I don't know about primer prep for aluminum. have only done steel. but here is my 2 cents

If you can get a good quality job for $200 (proper primer, color coat and clear all in high end automotive paint) go for it it will not be much cheaper doing it your self correctly.

Doing it your self you have two options: rattlecan...spray paint from auto store or home depot. etc or using automotive paints. My limited experience is that rattley can will me mor than you expect (ie two cans of primer, two of color, two of clear) because of overspray and doing many thing coasts. Rattle can can come out looking really nice but is not nearly as durable as automotive paint. Automotive paint either a sprayer or using a Preval (do it your self spray can) will give a much more durable finish but you will be over $100 on materials. The auto paint is much nastier chemically....you need a good mask...not just a paper filter.

the steps are same:

Clean frame, make sure all old paint is off, then degrease.

put coat of sealer primer on (on steel this is an acid etch primer...don't know eqivilant for aluminum)

put coat of filler primer on

put contrasting color coat of primer on

Sand until contrasting coat of primer is gone

Put multiple thin layers of color on (watching recoat times....if your go beyon recoat you will have to do a scuff sand)

Put mutiple layers of clear coat on, again watching recoat times

if rattle can...allow to harden a month or so before building.

RoboMonkey

I was just about to ask this same question.

If I want to spray automotive paint will a sprayer like this work?

Would duplicolor paint like this work with the matching primer and clear?

If anyone has experience with a setup like this or can recommend a durable brand of paint, that would be great.

Falanx

Two things -

Rattlecan jobs are always soft as poop, unless you're lucky enough to find two-pack-single-can type products - I'm not sure how available they are on that side of the pond, but I can imagine they're there if you look. I can't stress enough how important good preparation is though, as Squirtdad says.

Etch primer for aluminium alloys is also acid. In fact, often the same acid - phosphoric based. Not many companies selling a chromate etch vehicle anymore.

Aaron_F

Take it to a powder coater. ~$80 and zero effort on your part, and you'll get a great finish. I wasted so many hours stripping the paint off my frame, priming it, sanding the primer, and then painting. The job was perfect, but the paint was soft and didn't look pro. I finally said screw it and had it powder coated, and I'm extremely happy with it now. I even dropped a steel wrench handle on it by accident when I was building it up, and I have no idea where it smacked the frame, the finish is that hard.

Or just leave it bare, since aluminum doesn't actually need to be covered by anything.

nfmisso

+1 Powder coat.

Make sure take it to an experienced bike frame guy so that all the holes will be plugged (BB, headset, bottle mounts, etc); or make sure that you do that your self. If you get powdercoat in the BB or headset, you will spend WEEKS cleaning it out.

Another choice: have the whole frame Anodized.

or leave it bare aluminum. Clean it thoroughly to degrease (DAWN dish washing soap is good), rinse thoroughly, then dip is boiling water for a minute. This will create a thin oxide layer that will prevent corrosion. Warning - it may not look great.

rodar y rodar

Hmmm....
Aaron_F says that bare aluminum doesn`t need to be covered, which is was I thinking on reading the first post, but three other people answered between the OP and Aaron and didn`t contradict the statement that leaving aluminum unpainted is bad. So, is it important to paint, coat, or annodize an aluminum bike frame? Or will it do just fine nekkit?

Ramsey, my favorite paint for a super-low budget job on steel projects is a light coat of whatever primer from a can followed by two or three coats of that spray paint for patio furniture, no clear. I`ve used Krylon and Rustoleum versions, depending on which one has the color I want, and can`t tell much difference between them. It`s still "softer than poop", and I doubt it really seals very well, but it does keep the rust at bay on steel in my climate, and it seems to stay put a bit longer than "regular" spray paint, for whatever that`s worth. When it starts getting ugly, I give it another coat of patio paint. I would go for a cheap powder coat too, but unfortunately, can`t find one in my area who`ll do any job for under $100, and more if it involves masking off threads and bearing fits. You might try calling around where you live and see if you have better luck.

reddog3

I do a fair amount of bike painting- mostly for my own needs. None for profit, so I'm always looking for the cheapest and easiest way. I have compressed air, an exhausted spray booth, and several spray gun types. I've painted more than a few cars in the past forty years. So why wouldn't I just use this method for a bike?

I'm too lazy to do the necessary equipment cleanup for such a small job. Automotive paints are expensive and not readily available in small quantities for bicycle frames, so you always end up with stock and not necessarily in the right colors. Then there is a shelf life so waste is an issue. Consequently I'm always looking for the right "spray bomb" combination that is reasonably durable, and looks good.

Beyond good prep, primer is key. The best available in aerosols is 2k epoxy primer. The rub is cost at around $30/16oz. can. There's enough for two bikes in one can, so to reduce costs it's best to have two paint jobs lined up back to back, cuz once activated it has a shelf life of 4 days at best.

I'm currently getting really good results with the following products and procedures.

For the primer I'm using Plastikote "ETCHING" primer. It's sandable and fills good. Two decent coats, with the second being wet enough that the surface is smooth. If necessary you can sand out the runs. I dry sand the next day, then let it cure for a couple days before applying color. This is a lacquer product. Adhers very well to a properly prepped surface.

I haven't used this primer on aluminum so I can't speak to the adhesion issue.

For color coats I'm using Valspar "ANTI-RUST" "ARMOR." Two coats, one dry- one wet. No more than 15 minutes between coats. Walk away. Have a close look the next day. If the coverage is total with no thin spots, let it sit for a week. Generally though that isn't the case. That's one of the problems with aerosols for bike painting.

It's a complex set of joints and an aerosol doesn't lend itself well to getting full coverage of all tubes in tight places. You simply don't have the adjustability of a good small gun. Aerosols also put out lots of overspray, because you can't adjust it. To try and reduce overspray, and waste, you'll likely end up with a couple "light" spots in tight places- or you're gonna have a ton of runs to take care of.

So... I let it cure for a few days- wet sand with some "dull" 220, and give it another two good coats. You've now given it decent film thickness for sanding and buffingand covered the "thin" spots. Even though it's an enamel product, it's still sandable. After a week of curing I wet sand with 600, and buff with a good "clearcoat" polishing compound. Give it a couple good coats of wax.

I do not put down a clear coat, as I've not found an aerosol clear that was worth beans. Once you've buffed out the color coats, it appears as if it has clear on it anyway. Clear is only for filling so you can color sand and buff. Urethane clears of the automotive variety add durability, but we don't have that luxury in aerosols.

I've tried all varieties of aerosol combos, and what I'm doing now is the most durable to this point- and it looks good. It's been impact tested as well, and holds up very well. You can get a decent job with aerosols, just not as easily as with a spray gun using auto-paints. It takes a bit longer due to the necessary curing times- but it's way cheaper. A shade over $20 will get the job done. One can of primer, and two cans of color.

If your time is worth much however- I'd go the powder coat route.

Aaron_F

I bought a Gary Fisher SuperCaliber race frame in 1999, and stripped it the very next day. NEVER put anything on it but trail dirt, and retired it in 2009. Zero issues.

More pics: https://www.flickr.com/photos/one9us/...th/3300917091/

Falanx

I would be uncomfortable with an aluminium alloy frame in a high-strength aluminium alloy that were not in some way porotected. If I remember correctly the 1999 GF SC was 6000 series aluminium, no? Which is a) not a high strength alloy, b) a member of a family of alloys designed for precipitation hardening yet acceptable corrosion resistance. It doesn't suffer greatly from exfoliation like 7000 series, not pitting like 2000 series.

rodar y rodar

Argh! I should have considered that different flavors react differently. Well, I don`t currently have any aluminum bike frames (nothing against them) and none of my aluminum projects are pushing the boundaries structurally, so I guess I`ll just continue to not worry about finish.

Eric Estlund 

Aaron- it looks like your chain stay yoke might be cracked.

mudboy

I think that's a casting/forging mark where the flash wasn't machined off very carefully.

Aaron_F

Correct. Anyway, the frame served it's purpose for 10 years and has since been retired.

crnlmushroom

I dont know about yall but i wouldnt trust anything other then a powder coat on my bike. I found it to be the cheapest solution as well as the most resistant to chips. Just take to any automotive store that paints cars and theyll prolly due it for around $60 or so, just remember to tell them where to not paint.... its quite a b*tch to scrape off haha found that out the hard way

redclay

This is something I'm toying with, not yet serious about it. On a steel frame, is there any way to leave it unpainted yet protect it from rusting, just like a few have talked about for aluminum? My paint is horrorshow now, and I might be able to see "natural" as an improvement for very low cost. Any possibility?

unterhausen

no, it's really not possible from a practical standpoint. Steel on a bike rusts almost immediately no matter what you do. There have been people that have had clear powdercoat applied, but a pigmented powder coat is far superior.

redclay

I accept that--thanks. As long as we're talking about paint, what's your feeling about what a powdercoat might do to the very thin lugs on my bike frame. I know it's thicker than paint. Would it tend to make the lugs look less distinct than thinner paint would? I worry about my baby.

Falanx

The thing about pigments - and that's pigments in any paint system, be it two-pack epoxy, polyester powdercoat or whathaveyou is that it has a twofold method of operation. One, breaks the diffusion path for moisture through the coating to the underlying metal. It takes much longer for water vapour and air to diffuse through seemingly hundreds of individual layers of resin pigment resin pigment etc... Two, most pigments are insoluble salts of metals, or huge polar organic molecules, both of which offer some galvanic corrosion preventing benefit to a lesser or greater degree. They're coloured because they have bonding in certain areas of a particular strength, which so happens to correspond to energies in the galvanic range of metals...

unterhausen

that's interesting about pigments. I think the main reason that clear powdercoat fails is that all powdercoat has a very weak bond to the metal and thus allows rust to some degree, but you can't see it if the coat is opaque. I haven't heard of anyone complaining about the Speedvagens with clear powdercoat, so maybe they found the secret sauce. OTOH, apparently Rivendell has decided clear powdercoat is a bad idea.

jwpat777@hotmai

This is heresay as it were..I've heard a system of connecting apositive cable from an auto battery (or charger) to the product (the frame) and the negative termonal to the rattle can. Wha-la! Poor man's electroplating. (This might have to be metalflake paint to work.) Phase two: Purchase four heat lamps and apply enamel paint and bake it on. Supposed to be a rock hard shell coat. Phase three. . our local electroplater will guarentee work, as long as the product brought in is absolutly free of all rusty areas. Just my two cents...Thanks again for all advice given. Jim.

unterhausen

depends on the powdercoater, and to some degree, the powder. To really get a nice paint job on a lugged bike still requires a wet paint job. But a better powdercoater can make a fairly thin coat.

Falanx

The main reason any paint coating fails is the poor adhesion to an impermeable substrate. Powder's electrostatically attracted to the underlying metal, which give surperior cling to the purely fluid surface energy of liquid paint systems. Irrepective of bond strength, for corrosion to appear at the interface in an uroken coating, water vapour must be able to diffuse through the coating.

I've said before, all polymeric materials are permeable - in short, there's no such thing as a waterproof plastic.

The addition of filler slows down that diffusion, it's not really open to debate.

It is conceivable that the Speedvagen's powder is placed on a phosphate or chelated surface - it'd still electrostatically stick even to a metal salt rather than a clean metal. I've not asked them, and I doubt they'd spill if I did. And it'd take a lot longer for enough moisture to diffuse to start rust worms...