Painting your bike, the right way

If you ride long enough, you’ll want a custom bike, fits perfectly to your taste. Nothing beats a custom paint job.

Painting your bike seems trivial, believe me, it’s not. A great looking paint job may flake off in a matter of weeks if you have an aluminium bike, or your steel frame can show up rusty dots in a surprisingly short period of time.

I’ve quite a lot of experience with paint, as I used to paint almost everything, with every tool, and with every type of paint. I’m by no means a professional car painter, but I know it about quite a lot. Not just I paint things, but also seen a lot of cars getting painted, because I was a petrolhead.

Preparation and choosing the right equipment is everything. What I’m going to tell you may look discouraging or a insurmountable task, but it isn’t.

Before we dive into painting our frame or/and parts, we need to talk about paint types, equipment, etc. I’ll try to explain everything. It’s really hard for an amateur to get a grasp of types of paint, chemistry, tools, and auxiliary stuff like sandpapers.

Painting at a pro level is a daunting task, but results are very fullfilling. If you follow the steps religiously, you’ ll end up with a paint job, far beyond the few thousand dollar bikes!

Before starting, you should now that actual painting is just %10 of the job. A good paint is almost nothing more then cleanliness and good preparation.

Layers first!

A good paintjob consists of 2 types of primer, a basecoat and clearcoat, or topcoat instead of basecoat + clearcoat.

Why 2 types of primer? Well, even “primer” won’t stick every surface, let alone paint. Primer is a too broad term. It should serve 3 purposes: promote adhesion, stop rust / corrosion, and fill very fine imperfections that are otherwise show up with paint.

So, once we have the bare metal, aluminium or steel, we need to protect it from rust and corrosion. Also, even some steel, especially galvanised steel, is not suitable to paint or prime directly. Especially with acryclic paints we will use.

Your first layer should be either wash primer, etch primer or epoxy primer. Without any of them, paint will not simply stick to aluminium. You may think it is; but will fall apart real soon, take my word on that.

Second layer will be primer, technically, high solid primer. Most primers you buy in a spray can are high solid primers. These have some filling power, that fills very tiny

Sikkens 1K washprimer
Sikkens produces premium automotive grade products; and luckily we have 1K washprimer in aerosol form. They are far from cheap. Very far.

imperfections like sanding marks. Even you may not see some sanding marks, but they’ll show up in paint.

Once priming complete, you have to choose your paint. You can choose a topcoat, paint, and stop there. Or, you can paint a basecoat layer and add some clear coat.

If you’re painting metallic colors, you obviously have to clear coat. For solid colors, you don’t need a clear coat, but clear coat have some advantages. First, the looks: although some quality car topcoats can be very shiny, they cannot match the “3D”, “liquid glass” finish of a clear coat. Second advantage is, if you apply few layers of clear coat, you can polish it once it loses its shine. With every polish, you’ll be removing some clear coat; so in the end, you’ll have no topcoat at all – maybe after 10 or so polishes. Yet, you can re-apply clear coat over it. With topcoat only, you’ll lose the paintjob. If it’s a complex one with few colors, or some graphics, that’s a wasted effort. I always prefer the basecoat + clearcoat combo.

You don’t need to buy a basecoat. You can apply clear coat over a shiny topcoat, too.

Another advantage of clear coat is, it protects your decals and make them look as if they’re part of the paint.

Compressor or rattle can?

I always prefer a compressor / spray gun combo. There is a bit of investment involved, but if you’re an avid cyclist, you’ll need a compressor anyway, at least for seating tubeless tires. A 50 liter compressor is adequate for frame painting, if you don’t go for HVLP guns. Take my word and buy a conventional, old school gun: they’re very cheap, finish quality is very good, if not better then HVLP and can be operated with smaller compressors. Their only disadvantage is, overspray. They waste paint. Since you won’t be painting bikes every day, and amount of paint needed is minimal, that is not a huge setback.

Rattle cans seems attractive, but they have so much disadvantages:

  • You get low quality stuff, compared to a automotive grade paint / primer / clearcoat.
  • Your color options are limited.
  • They are mind blowingly expensive, compared to spray guns. A rattle can hardly have 100ml of paint, generally at the price point of a half liter automotive paint.
  • You won’t get the same results.
  • Some stuff is not available in rattle can form; or prohibitively expensive, or very hard to get your hands on. Especially clear coat. 1K (more on that later) clearcoats are not shiny, hard or UV resistant as automotive grade clearcoats. I’ve seen 2K rattle cans. These are 2 cans in a one can, actually. You push a plastic part at the bottom, and the clear coat mixes with hardener. You have to use it in a few hours, otherwise it sets.

Once you have your compressor, you’ll need two spray guns, or a spray gun with 2 nozzles. Primer guns have larger nozzles; while you’ll use the other gun / nozzle for etch/wash primer, clear coat, topcoat or basecoat.

Nozzle sizes differ for paint types and gun types. 1.3mm nozzle is ideal for conventional gun for all types, except filling primer. I use 1.8 for primer, because that’s what I found for cheap, and quite close to “ideal” 1.7mm for the paint system I use.

It costs me about 25-30$ to buy 2 spray guns.

You’ll need a pressure regulator and water filter. Attach them to your gun side, not compressor side. They work more efficiently. I paid 10$ for an “acceptable level” regulator + water filter combo.

For under 250$, you can buy a whole set, including a silent 50 lt compressor, 2 guns, filter, regulator, hoses and couplings.

Paint types – what is 1k, 2k, 4k, 5k ??

It looks like a very confusing thing. I was shocked to see that even most “DIY sites for amateurs” do not explain this.

All acryclic or urethane automotive paints comes with “hardener”. Without hardener, paint won’t dry.

1K paints, like laquer paints, do not need a hardener.

2K paints, being the most common type, are mixed with 2 parts paint, 1 part hardener…

4K? Easy. 4 parts paint, 1 part hardener!

Easy as that!

Hardener is not “thinner”. You can generally add up to %10 thinner to the mixture if you need.

Hardeners generally come in 3 forms: slow, standard, fast. Some brands have “extra slow” and “extra fast” hardeners in their paint systems.

I use fast or standard hardeners, because I don’t have a  paint booth. Faster the hardener, paint dries faster. So less risk of paint getting dust particles. Also, “slow” hardeners are “too slow” to be used outside paint booths.

Thinners come in same grades as hardener, too.

Laquer, acryclic or urethane? Water based or solvent based?

Well, the best paint chemistry on earth is probably urethane; but it’s totally unusable for an amateur. It’s extremely poisonous. (Contains the same chemicals used in super fast glues) Do not ever attempt to do it. Even the pro-grade automotive paint booths are different for urethane paint; they have far superior ventilation and filtration systems. Luckily enough, they’ re also extremely rare. However, hardeners in popular acryclic paints also contains such chemicals in some degree. Paints are dangerous.

Laquer is an old school paint. It does not come with many color choices. They have nothing superior to acryclic, except being easier to use, as they do not need a hardener, and barely need a thinner, too. Most of them are premixed these days.

I only use washprimer in 1K form; because my paint system does not have any other viable option.

Water based paints are up to 3x more expensive, and not as clean as they’re advertised! They’ re as poisonous, in fact, some are more poisonous as their solvent based counterparts. The only advantage is, they have less vapours.

Am I ready to paint now?

Not yet! You’ll need a gas mask rated for chemical vapours. Also, I highly suggest wearing glasses that covers your eyes properly. Also, do not forget to cover your hair. A baseball cap will do; but a buff may be better.

I presume you have your compressor connected and ready; along with your protective equipment.

Before shopping for paint and primer(s), here is also what you’ll need (and why):

  • Masking tape, obviously for blocking paint going into the wrong places like bottom bracket shell, head or seat tubes, etc.
  • Mixing cups with measure, so you can mix paint, hardener (and thinner, if you need) in correct ratios.
  • Mixing sticks, preferably stainless steel.
  • Prep solvent, AKA cleaning thinner. This is different from thinner for your paint system; designed specially for cleaning surfaces before paint. Removes silicone, dust, grease.
  • Strainers, for filtering your paint / primer mixture.
  • Tack cloth. A cloth with wax, that grabs dust particles (or flies!)
  • Paint gun stand (optional)
  • Sandpapers. 320,400,600,1500 and 2000.
  • Rubbing compound. You’ll need this after paint fully cured.
  • Polish / wax
  • Paint remover

Prepping for paint

You’ll be probably painting frame first. I do not paint “valuable” components; like parts which are considered “classic” or, the parts you’ll be proud showing off 🙂

I also do not paint carbon fiber parts; because I’m not sure about doing it right. To be honest, I don’t bother painting them because I like the texture, too.

I won’t be getting into details like decals, making stencils, painting few colors together, making graphics, etc – I do not consider myself an artist. I am not qualified enough to talk about decals or printed matter.

Before you start, dismantle everything that is removable, including headset cups, bottom brackets, even brake bosses, if you have them.

Remove everything to bare metal, preferably with chemical paint remover. You’ll want to brush a thick coat, remove what can be removed without scratching the surface. I suggest using some plastic cards, like credit cards. If you scratch anything, you’ll have to fill it with body filler. We don’t want that. Repeat until to get to bare metal.

Start painting!

  1. Wash your frame with dishwasher soap religiously. Pay attention; we have to remove any grease deposits left in head tube, seat tube, or bottom bracket shell.
  2. Once dried, wet sand with 320 grit sandpaper to make sure its spotlessly clean. This process will also boost adhesion.
  3. Wash with dishwasher soap again. Let it dry.
  4. Tape everything where you do not want to be painted.
  5. Position / hang your frame, so you can access everywhere without touching it. You can use something like a tripod with an extension that fits into headtube, or just hang it from headtube, or rear. Whatever suits you…
  6. Now, you should get your compressor, paint gun and etch primer / epoxy primer ready. I use 1K primer; I can spray it right out of the can. If you use epoxy primer, you have to prepare your primer beforehand. Switch on your compressor while mixing your etch / epoxy primer. Fill your spray gun. Do not forget to set your pressure regulator according to paint and gun manufacturers’ directions. In this step, I assume you’re familiar with your gun, compressor and primer / paint, or whatever you’re spraying. Never fill your gun and start spraying without prior practice. Setting your spray gun and everything right is a dark magic thing. Practice on a metal plate. Do not practice on cardboard, or any other material that will absorb liquids; it won’t give you any feedback on air – liquid mixture; you’ll just get the spray pattern right.
  7. Wipe the frame with tack cloth, then prep cleaner, or cleaning thinner. When wiping, wipe in one direction, and do not wipe back – this motion spreads the nasty things like silicone, instead of removing them!
  8. Spray a wet coat of etch primer, or epoxy primer. I prefer etch primer for many reasons: its easier to handle, creates a thin coat so does not have to sanded afterwards, and instantly ready for another coat. If you’re spraying epoxy primer, you have to wait at least 4 days to spray anything over it! When I use 1K etch primer, generally one coat is enough for aluminium, but I spray 2 coats. Follow manufacturers advice.
  9. After the etch primer cures, prepare your primer. If you get it right with etch primer, you do not have to sand, but frankly, this is hard to get it right. How do you know if you need to sand it? Rub your fingers slowly all along the frame, not skipping any milimeter! If you feel anything very slightly bumpy, that needs to be sanded. Anything you feel with your fingers will show up like an ugly bruise in your next coat, do not doubt it! If you have to, use 320 grit. Wash your frame again, if you sand something. Otherwise, wipe with prep cleaner and spray your primer.
  10. I spray primer at least 2 coats, almost always 3. Remember, we are using primer for absolute perfection. Sand with 400 grit. If there are very tiny imperfections, thats ok, but you have to keep your lines sharp; if you have bends, bevels, sharp turns in your frame. Spray two coats now; with 15 to 30 minute intervals, depending on your hardener type and manufacturer recommendations. Most high solid primers are sandable in a few hours; consult your manufacturers directions again. Now, you have to sand it as your life depends on it. Wet sand 320, then 400, then 600 grit. (Even most pro auto painters stop at 400, but go ahead).
  11. You should have achieved absolute perfection by now. If not, sand a bit more aggresively, spray another coat, and start over again.
  12. Wash your frame rigorously, as you’ll be applying basecoat + clearcoat, or topcoat now. Let it dry.
  13. Prepare your paint.
  14. Wipe it with tack cloth, then prep solvent.
  15. Paint! If you’re going to just topcoat it, I advice to spray 3 coats. Your first coat must be “dry” – spray a little bit less paint. We do first coat for other coats to stick! If spraying basecoat + clearcoat, or topcoat+clearcoat combo, 2 coats of paint is more then enough. Wait between coats. 20 minutes is well enough for normal hardener in a hot day (over 25 degrees Celcius)
  16. If you’re spraying clear coat, you have 2 options: either spray when paint is wet (wait at least half an hour after last coat of paint) or, wait a few days, wet sand with 1500 and 2000 grit first, then paint afterwards. I know this is painful, but gives the best results. I spray 1 dry, 2 wet coats. If I need extreme gloss with some “3D” look, after the last coat, I wetsand 1000,1500,2000 and 3000 grit, and spray another 2 coats! This is crazy. Don’t do that. It’s only advised for crazy people. Not you.

Congratulations! If you made this far, you have a nice, super shiny paintjob that is admired by Rolls Royce owners, or a pretty disgusting abomination.

Now, ride your bike shamelessly for a month while the paint fully cures, because we don’t have a paint booth, or infrared heater. After that, give it a good rubbing compund, polish and wax combo – Iets talk about that later.

If you want to go extra-hardcore, showroom like quality paintjob, let the primed parts wait for about a week or so. Then paint as usual. If you’re using clear coat, wait 2 weeks between basecoat and clearcoat. Actually, this is not for the looks. This is for longevity. If you choose this route, you’ll have a very hard paint that can withstand anything you can imagine!

What if I only got rattle cans?

Well, you can achieve the same look; minus shine and longevity. A 1K paint, especially clearcoat will not be that shiny, or hard, or UV resistant; but still, it can look great. But say, Mercedes-great; not Rolls Royce-great…

Steps involved are the same: you need same materials, same amount of labor. Sanding still is the key.

Please never skip etch primer step. Luckily, there are some etch primers comes in cans. In fact, premium brands like Sikkens or Standox have them. They’re expensive, though.

Rattle can paints can never match the quality of automotive paints. You’ re also limited in some other ways, like additives. There are many kinds of additives that you can add to an automotive paint for specific purposes. Like, extra hardeners. These are not the hardeners I mentioned before. Those are the chemicals that add extra surface hardness to the paint; which is obviously very handy for bike painting. There are some additives that has to be used with elastic parts; so paint does not crack.

Is there a proper way for lazy riders who want great paint jobs?

Yes. Lightly sand the painted part, starting from 320 grit, then 400 grit, then 600 grit. Fill any holes if there are, with putty. Sand it with 400, then 600 grit wet.

Since you did not remove all paint, paint will stick fine. But primer first. You don’t need etch primer; in fact, it shouldn’t be used on paint. Prime, and follow the directions for prep work. Wash, then paint.

This method works fine if you do the prep work carefully. You can either use aerosol paints (rattle cans) or spray guns.

However, stripping down to bare metal first works wonders if your parts have sharp corners, contoured edges, etc. Generally, paint from the factory is not perfect. If you do it by the book, you’ll get much better results.

Electric paint sprayers work?

Yes and no. You need to have a premium model which can spray solvent based paints. Those are the ones with brass needles, brass caps, quality plastic caps, etc.

I never sprayed auto-grade paint with electric sprayer, but can confirm enamels work myself, to some degree – its a very dirty, tedious task. And since enamels don’t flash in minutes like acryclic or laquer paints, you may expect to have lots of dust and bugs on your painted part!

Also, nozzles should match the viscosity of your paint. If everything goes and matches perfectly, you’ll end up with a paint having huge orange peel problem.

Even premium cars right out of the factory have orange peel problem to some degree. What you have to do so is, wet sand with 1000, 1500, 2000 grit papers in succession until you reach glass smooth surface. Then polish. It’s possible. In fact, you may even use rollers (not with acryclic auto paints, but some enamels), then wet sand hysterically to achieve mirror-like finish! That involves lots of wet sanding, re-applying coats, sanding again, and it may take up to a week, as most enamels require 24 hours to cure.

Hey wait! What about matte finishes?

Matte finishes are achieved by matte clear coats. There is nothing special about it.

I advice you to make a test sample before spraying matte clear coat; as it is harder to achieve desired look. Every matte is..not matte is you may think.

What about those weird colors that change under sun or shade?

That’s called chameleon paint. Nothing new; I see some custom painted cars with it, at least 25 years ago.

Think it as a metallic paint, having flakes, but in different shades. I have no personal experience with it directly; but I suspect it requires different skills to do it right, as alignment of flakes is what makes the difference.

You need to take care of your paint well, after spending such time and money to the project.

Happy riding, with no fumes!


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