+/- of using automotive paint
Automotive paint is much more durable than hardware store spray paint but it is not as strong as powdercoating. However, it allows for easier detail/color work and may be cheaper than powdercoating. It is more expensive than standard rattle can paint but it dries relatively fast where rattlecanning requires a full day to dry between different coat types.
Stuff you’ll need
Respirator - Automotive paint is really toxic and this item is very important to have.
Degreaser - just use any spray degreaser you have
Latex Gloves - once you degrease the frame, you can not touch the frame with your bare hands
Twine - used to hang the frame
Sand paper - 200-225 grit and 600 grit
Tape - if you plan on doing any masking, I used the skinny 3m tape for detailed work and normal masking tape for the stuff inbetween
Tweezers - just in case something lands on the paint
Plastic to cover stuff in your garage/workspace
A person to help you (optional) - Having some one else around helps to point out spots you might have missed and other details you forgot about.
Automotive paint - just go to any auto paint shop in your area to get the paint. Try to find the place with lowest minimum because you only need 3-5 onces of paint for the frame.
Reducer
Preval sprayer - the automotive shop should have this
Primer - Buy the good stuff to make the paint more durable. Ask the automotive shop for their recommendations.
Clear Coat - Don’t skimp out on this either
Most of the following guide is from an email my friend Mike sent me to help me paint my frame. I added a few things that I discovered when I did it.
Prep work
Find a nice open, well lit, and ventilated place to paint your frame. Cover anything you don’t want paint on with plastic. If you are working in your garage, the guy at the automotive place suggested watering the ground to prevent dust from flying in the air. As for the frame, you want to use the 200-225 grit sand paper to scuff up the metal to have a good surface for the primer to stick to. Now you want to hang your frame/fork using the twine.
[size=85]My friend Mike’s bike[/size]
To hang the fork, tie a screw or other small weighted metal object to the end of the string and drop it through the tube. Now use a spoke or coat hanger piece through the brake hole to support the fork. For the Frame, use the same weighted object to drop the string down the headtube, through the downtube, and up the seattube. Now is a good time to put on the latex gloves. Now you want to degrease the frame. Take a damp rag and wipe of residue from the degreaser. Now take a dry rag and clean of the remaining moisture. (If you touch the frame with your bare hand, the oil will prevent the paint from adhering to the frame) I don’t know if this very necessary but it helps it feel more professional and will probably help with chasing/facing later: After hanging up the frame, I like to stuff the bottom bracket and other open tubes with newspaper to prevent paint from building up inside.
Primer
OK, so now you’re ready to spray your first coat of primer. On with the respirator, shake your can, and do a couple of test sprays away from the bicycle. You don’t want to waste a lot of primer this way but it’s preferable to get a feel for the way the can sprays before you go straight to the metal. Also, if it sputters or spits - you don’t want that to happen on the frame. If the tip is blocked, and this goes for the clear coat as well, turn the can upside down and spray a little bit to hopefully clear the head. Keep the primer can about 12 inches away when spraying but always start farther away if you’re uncertain. Thin application is better than a run. I don’t think you should have any trouble with the primer though, its application was fairly easy for me.
You may or may not want to use this technique for the primer coats (again, I think they’re easier) but definitely for the color coat. > Start spraying off the frame and then pass the spray over a tube, off the frame, and then stop. If the can is going to spit or sputter it’ll have done it in the air and not on your tubing.
When you’re spraying (primer, color, or clear), start with the most difficult areas to reach first. These are generally the joints, especially the bottom bracket. I feel it’s best to overemphasize these areas when you’re spraying. Because they’re tougher to get to they’ll receive less attention. Not because you’re not being conscientious. But because of the physical constraints of the frame. If you bias towards those spots you’ll probably end up getting the right amount on them. Another area to watch for: undersides. Depending on how the bike is suspended you’ll probably have to stoop or crouch to spray some of the tubes. These are areas you should bias towards as well.
The first coat of primer will be fairly easy in terms of contrast - just make all the metal disappear. At the paint shop they suggested immediate respray times. I would suggest 15 minutes or so if you’re going directly to the next coast just to be safe. There’s nothing negative about waiting the few extra minutes. You’ll probably need 2-3 coats of primer.
If you’re going to spray a coat of primer and not immediately do the next coat, say you’re waiting a day, you’ll need to rescuff the first coat with a 600 grit sandpaper. This is the method that I used when I first painted my Centurion. It’s up to you if you want to pursue it, but it essentially means: primer, wet sand, primer, wet sand, color, wet sand, color, wet sand… You get the picture. This is the way the professional painters do it, sanding between every or nearly every coat, but you have to decide if you want to to the extend the timeframe of the actual painting. It will extend that window significantly. Maybe you could get better results but you’ll sacrifice any of the speed increase of the automotive paints.
Painting
After finishing with the primer I would recommend waiting 30-45 minutes before you go to color. The guys at the paint shop suggested a 1 to 1 reducer to paint ratio. I would try that and make sure it’s not spitting. You may prefer to add more reducer. I would take a spare piece of cardboard and do a little bit of test spray with the Preval so you get a sense of how it works, its spray characteristics, etc. If the Preval is spitting then the mix is too thick and you should add more reducer.
Don’t shake the Preval sprayer while you’re using it. It’s kind of a delicate piece of equipment and it isn’t held together all that strongly. I got into a habit of shaking the cans to try and vary the spray but that won’t work with the Preval.
Keep it light. It may seem like you’re not getting any paint on the frame at all, especially with the lighter colors, but you have to keep it light. The color will build up over several coats and it’ll turn out fine in the end. If you get anxious and want to see it build up too quickly you’ll run the risk of runs.
A word on runs: If you do spray too heavy and you end up getting a drip it’s bad news. It’s just about impossible, with the methods I was using anyway, to totally remedy a run. You can try to dab it with a paper towel or a sponge but the consistency is not going to be smooth and you’ll most certainly notice the defect afterwards. Will casual observers notice it? Maybe not. I had a fair amount of success touching up a couple places with a very thin paint brush and the straight paint. If it’s bad enough now though you’ll have wait, strip it, and then repaint. If you get lucky you can strip just a small section instead of the entire frame.
Always do the fork first. If you mess something up the fork is small in comparison the frame. It should be the test subject. If it all goes to hell so what? Just strip it and do it again. Fork first. Always.
A note on touch ups: Do not use the paint/reducer mix for touch ups. The reducer is paint thinner. It eats paint. If you expose it to the paint already on your frame it’ll eat it. It’ll be awful. Use the pure, unadulterated paint straight from the can if you need to touch up. I got surprisingly good results.
For your color application I would suggest three coats for everything but especially three coats for your lighter colors.
Another caution: Be really careful about where you are when you’re painting. Not location, where you are. That means your limbs, the things you’re holding in your hand, etc. It is a real downer to clink the frame when your attention slips for a second and see a big smudge in the drying paint.
Between coats of the same color the paint shop guys said you can go with immediate reapplication but that made me kind of antsy. I would wait about 15 minutes.
Masking
If you’re switching to another paint color and you need to do some masking I would wait 35-45 minutes before taping the frame. You cannot use too much tape when you’re masking the frame. This is another step of the process that should not be shortchanged. Do not rush the masking. I thought I was doing an adequate job masking for my different paint colors but I still ended up with some overspray in a couple spots. Don’t do an adequate masking job, do a tremendous job. Masking can be very annoying when you are working with something detailed like lugs. I would suggest taking off you gloves to mask because the tape will just stick to the gloves and piss you off. So if you do this, make sure to degrease the frame before you spray on the next coat. (I forgot to and it was horrible) Be absolutely, totally confident when you’re finished. Spray paint is incredibly good at drifting into spots that you missed.
Clear coat
OK, so you’ve got all your color on the frame now. (Hope I haven’t left anything out.) It’s time for clear coat. The clear coat will be a very thin spray so I would recommend three coats. There’s a kind of wet shine finish you can get if applied properly. I was a little skittish about over-application because of runs I had earlier. It’ll be up to you to say how much is too much. I got very antsy about some very wet looking sections that I could’ve sworn were going to run, but didn’t.
Now, the professional places have ovens that they use to bake the paint once it’s on your bike. However, if you are like me, you don’t have access to such an oven. Instead, I laid the frame out in the sun for one day for each side. This probably doesn’t make the paint as tough as it would be if it were baked, but it should do well enough, especially if you live in a hot, sunny area.
bike painting links
Joe Bell:
http://www.campyonly.com/joebell/how_we_paint.html
http://www.campyonly.com/joebell/painting_steps.html
Bike Restorer with the homemade space heater oven:
http://www.nonlintec.com/bikepages/
A guy on Instructables.com that I read before trying it:
http://www.instructables.com/id/Bike-Painting-Tips/
