Al;ternative to shotblasting old frame

SamuelRemings
SamuelRemings Posts: 76
edited October 2009 in Workshop
Hi there

Still very new to this forum so excuse me for any ignorance that may be exhibited on any cycling subject :roll: .

I have an old 1979-80 Claud Butler Majestic with a frame that needs some work on the rust. Now, I've had some good quotes for a shot-blast and then a respray but being the way I am I want to get my hands dirty and in the process save money that I haven't got. The one resource I have more of is time so...

...is there a good alternative to shot-blasting a frame? Has anyone had any luck with using chemicals to treat, strip and prepare a frame for painting and if so what are they and what is the process? Is it as good as a shot-blast and what's the time span? I'm happy to try any method that means I can do it because after looking into hiring the equipment for blasting, I've found it's economically a complete waste of time (and if they're industrial strength machines the pressure will be too high anyway).

Second question, once this stage is achieved has anyone had any luck with using normal spray cans (quick dry enamel) or is this a naive step in the wrong direction? Again I could probably get it powder coated at a good price but I'm very obstinate when it doesn't involve me. I'm used to using spray cans on other projects and am not bad but also wondering on the time scale between one coat and another. So has anyone tried this?

Any answers will be most appreciated.
Cheers
Sam

Comments

  • lae
    lae Posts: 555
    Yep I've painted a dozen bikes and a few cars, it's really rewarding.

    You can strip a steel frame really easily. If you have an electric drill, get a wire cup brush/wire wheel (wheels are a bit better) and a 'manual' toothbrush sized soft wire brush. Get some nitromors and slap it all over the frame as per the instructions - after a while the paint will start to bubble off and becomes really soft. Attack it with the drill/wheel, using the wire brush to get into the little areas where the drill can't reach. Messy, but within a couple of hours, you'll have a pristine stripped frame. Wash it in very diluted soapy water and dry it very thoroughly, and you can begin painting.

    As for painting, you can get very good results with car paint spray cans (which are cellulose or acrylic based, not enamel since the 1950s!), but it just takes a bit more work and if you're doing more than a couple of bikes it's probably cheaper to buy a compressor and spray guns etc (I bought my first compressor and gun set from Aldi for £80 and managed to paint a car perfectly acceptably with it). All spray can paints etc should be available at a motor factors. I would recommend Hycote paints and primers - Halfords colours are alright but their primers are very watery.

    Anyway

    You need to protect your steel with red-oxide primer (basically a waterproof sealing primer). The steel should be well scuffed by the wire wheel, but use a soft lint-free cloth (i.e. old t-shirt) and some degreaser/thinners and wipe it down, just to make sure there's no grease or oil or dirt left. A few coats of this, waiting 15 mins between coats, and you're done. Dry for 24hrs (drying times are for storing the bike in a warm place like a heated garage - if you're drying outside (which I strongly recommend against) or in the shed, double them)

    Now is the time to fill any little nicks or scratches or dents in the frame, using bodystopper (fine filler). Use per packet instructions.

    Then you can apply a few coats of filler primer, in the same way as before. This is essentially a thick paint. You need to sand it to a smooth finish with some 800g sandpaper (with plenty of water and a drop of washing up liquid to stop the paper clogging). If you sand through, you can always apply more paint, but be careful around edges as they are particularly easy to sand through. Wait 24hrs, then -

    Then apply colour primer (white, black, grey or sometimes red) in much the same way, five or six thin coats, wait for 48hrs before sanding with 800g

    Then apply colour, lots and lots of coats this time - I usually use six cans of colour on a bike that I'm doing 'properly', usually waiting 12 hours between each can. Dry for 48hrs, then sand with 1000g, then 1500g, then 2000g to get a really smooth finish.

    If you're using a metallic colour then this is the time to apply a lacquer (protects the little metal flakes which can oxidise very easily - when you see an old car bonnet that's gone all milky it's usually because the lacquer has lifted and the metallic paint has started oxidising). 3 or 4 cans here, same method as colour, sand up to 2000g again.

    After your top coat has cured properly (give it at least 48hrs in a warm place, or a week hanging up in the shed) then it's time to polish it. You can get little bottles of polishing compound, or if you've got some T-Cut lying around you can use that (dilute the T-Cut a bit though, it's somewhat harsher than polishing compound). Follow the instructions on the bottle. You should end up with a beautiful shiny frame.

    Hope that helps
  • lae
    lae Posts: 555
    If you want to do a quicker and cheaper job, you can cut down on a lot of the sanding, which also means you'll be able to get away with less paint. You can paint a bike with a couple of cans of primer, three cans of colour and (if needed) a couple of cans of lacquer, and just one quick sand and polish at the end. The finish won't be as good, obviously, and it won't be as robust, but it's much cheaper and faster. Good for getting an old frame on the road quickly, or trying out different colour schemes.

    Matt black will also cover pretty much anything, in one coat, and needs no finishing :D although I guess the street fighter look isn't what you're going for!

    One last thing - make sure each step is absolutely perfect before moving onto the next one. Car paint isn't like house paint - it's extremely thin and very glossy, and tends to highlight small imperfections rather than cover them up.
  • SamuelRemings
    SamuelRemings Posts: 76
    Many thanks to both of you, that has been extremely helpful.

    Cheers.
  • lae
    lae Posts: 555
    It was me both times! Post pictures of your bike when it's done, sounds like a good project
  • SamuelRemings
    SamuelRemings Posts: 76
    Very helpful Frink, have the bike stripped down and that wire wheel was invaluable. Many thnaks to you for that and I will post photos once finished.
  • mikeyboy12345
    mikeyboy12345 Posts: 187
    Good luck Samuel! I too will be interested to see pics and read of any tips/problems you discovered, including cost of materials, etc., as I am considering the same sort of job on an old Raleigh Banana.

    Frinkmakesyouthink: what's the best way of getting the decals to look as though they're part of the paint job, as opposed to simply stuck on? Is it just tons of lacquer over the top? Will the "ridge" (ever-so-slight thickness of the vinyl) be visible under the lacquer? If the decals ARE PVC then will they react with any paints/lacquers?
  • Wappygixer
    Wappygixer Posts: 1,396
    If you can find a paint shop then I'd buy paint from them.
    Most can put the paint of choice in a aerosol.
    Their paint is of a much higher quality than off the shelf paint.
    Its a little mor eexpensive put coverage etc is much better as is wear.
    Its mostly based on 2 pack which used to be laced with cyanide which is deadly but its now no longer added and is perfectly safe to use.
    Which ever way you paint be sure to wear a proper mask to protect from both the paint particles and the gases given off.
  • lae
    lae Posts: 555
    mikeyboy12345 wrote:
    Frinkmakesyouthink: what's the best way of getting the decals to look as though they're part of the paint job, as opposed to simply stuck on? Is it just tons of lacquer over the top? Will the "ridge" (ever-so-slight thickness of the vinyl) be visible under the lacquer? If the decals ARE PVC then will they react with any paints/lacquers?

    Oooohhh... tough one. I dislike decals (being an arty-farty-poncy vehicle design student I think they 'ruin the lines' or some toss like that) so none of my bikes have any except for some little metallic Reynolds 531 ones which I just stuck on afterwards...

    I'd say, test it out. If they are water slide (not water slide, but you know what I mean, like airfix transfers) transfers then they're so thin that you can probably lacquer over them and not notice anything, OR if you do, lacquer it loads of times and sand it flat with 2000g. PVC decals are much thicker and there's no way you'll get enough lacquer on to get a smooth finish. You might have to stick them on the outside, or get some water-slide transfers made up (lots of companies do them).
  • mikeyboy12345
    mikeyboy12345 Posts: 187
    Cheers Frink! The decal set I'd assumed I use would be a factory NOS PVC set. Didn't realise companies would make a facsimile waterslide set (I used to make a lot of Airfix stuff, no hassle :) ) as I assumed this would violate copyright.

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