msl109

Hi folks - I'm in the midst of refinishing an old Raleigh International in a copper finish - I wasn't looking to put a tremendous amount of time or dollars into it - I got it cheap, and it's not a museum piece, but it's in very decent shape. I'm usually pretty good with a rattle can, buffing out the final clear with cutting and polishing compounds, so I decided to go that route.
It had been refinished in a terrible yellow color, but the finish seemed to be a pretty stable base to prime over. So I sanded it with an 800 grit until it was no longer shiny, wiped it down with naptha, and shot it with a couple coats of red Dupli Color filler primer. After a week, it still failed the thumbnail scratch test.
So I've resanded it with 320. Wondering if I should use a different primer this time or if my expectations for the hardness of a primer coat are a little too high. I'm thinking once the base coat (Dupli Color metal specks - much more a subtle metallic than "specks" ) and a good clear are on it, it should be ok and only harden over time. Looking for opinions and advice on a good clear in particular- willing to spend more for something better than what your average auto parts store sells. I once not too long ago cleared a frame with Krylon acrylic lacquer and the stuff never hardened - not over months, not like this primer, but sticky. I do have a can of clear Nitrocellulose lacquer I finished a guitar with, but don't know how durable that would be on a bike. Anyway, the Krylon was terrible stuff that makes me hesitant to use anything they make. Looked it up on Amazon, and my experience isn't unique.
As to the base coat, this really seems to be the best match for a color that's hard to match, so I'd like to use it unless strongly advised not to. Open to all and any suggestions and all are appreciated.

Btw, I know someone likely will tell me I should strip it to the metal and start over with higher quality paints. I'd really rather not, mostly because of the time I've already put into it - I've sanded it more to perfection than I ever expected to, but starting over isn't out of the question. Please tell me I don't have to.

BlazingPedals

I'd sand it to bare metal and start from scratch. You don't know what kind of paint is there.

msl109

I don't, no, but it's hard and not deteriorated at all - pretty sure it's an enamel. No peeling or deterioration of any sort when sprayed over. And the frame was originally well-primed under the yellow - bond is good. I'm thinking the issue may be in my application or quality of primer I'm using. Or 800 grit was too fine to ensure a good bond?

LuckySailor

Couple things. As a painter, when paints and lacquers don't get hard, it generally because the product is old. Or it wasn't properly stored. IMO, your question to get answered is best presented to the manufacturer of the product. Your technique is fine, and should have worked. The filler paint you're using will add many mils of paint, and probably will create issues when tightening your BB, and possibly brake callipers, etc. At this point, I suggest to sandblast frame for $50, prime, paint and clear. I don't piddle around with multiple layers of coating either. Sandblast, prime and paint.

msl109

Thanks - I called Krylon when I had my disaster with their clear - it was a brand new can at the time (or at least newly in my possession). They were worse than useless: "try wiping some thinner over it to dry it or just spray it again." What??
Don't know if Dupli color would be any more useful.

My issue with sandblasting is possible damage to the chrome - the lugs up front are chrome. They look painted over but right now are sealed with a liquid mask that peels off. Is there a way to ensure the chrome is protected when sandblasting? I've thought of dip and strip but I'm not sure who does that in my area and what they would charge. Maybe I should just go at it with aircraft stripper and a suit of armor .... it also wouldn't take much to manually remove the primer I've applied and get back to the yellow. My guess is some thinner and steel wool would do it. But I hear you about multiple layers not being ideal.

I'd say the primer is about 2 years old. That could be it. Soft may not be the right term. I can scratch it off with a thumbnail (after about five or six passes) or sandpaper, but a thumbnail pressed straight down doesn't leave an impression. It is dry to the touch. the paint doesn't stick to bare metal any better than it does to the yellow paint. Wasn't worried about the thickness at the BB because I was going to chase and face it and the head tube anyway.

If I do strip it one way or another, do you have any recommendations for a primer, paint, particularly clear?

LuckySailor

Masking Tape over the chrome, and care not to concentrate in those areas with blast media and it'll be fine. Touch up with steel wool as necessary before priming. I had new S&S couplers to blast around, and all turned out fine.
Make sure that you are not mixing water based paints and oil/solvent base paints. When you apply your finish color, let it set for about 45 minutes, (not cooking it in the sun either!) and then hit it with the clear poly, and let dry. This will adhere the poly to the oil paint, and you will avoid peeling down the road. If you let the oil paint dry, then sand as you have done before to get rid of gloss, and then hit it with the poly.
I used to use Zip Strip and steel wool on cars, but haven't done so in years. I would think that you are well beyond the window of opportunity to use mineral spirits and steel wool to clean off primer. If you can, that would confirm old material. The bikes I've refinished in the last several years have been sandblasted, including a brand new Trek 520. And the last bike was powder coated- $100 (CDN). And the next one likely will be too (if I decide to repaint.) That bike is in really nice condition- 1968-9 boys bike, that I am adding a center shifter, and a 5 speed rear end to and a New banana seat. Cool, fun project.

msl109

Does sound like a cool project ...
I'm sure at this point you're right about the old material - I wiped it down again with naptha -- and to my amazement the primer came off on the rag ... How long is this stuff typically good for before you should toss it ? I've used other pants that have been sitting around for a few years and have had no such problems.

I'm pretty sure that if Naptha took the paint off, steel wool and thinner would probably remove it all. But I think at this point I'm going to take it down to the steel. if the original paint and primer come off easily with a stripper like zip strip then maybe I'll go that route. if not I'll go the sandblasting route and do what you suggested. Thanks for all the help - I'll let you know how it comes out.

capnjonny 

If you have a compressor you might think about buying a inexpensive sand blast kit. the gun and hose is available online for about $26. and the only other thing you need is a 5 gal. bucket.

I use a similar blaster I bought years ago and I find it easier to use than sanding.

What I do is first take an orbital sander and sand off most of the paint , then use the blaster to get the rest of the paint off. It works especially well to remove pitted rust.

Once the frame is stripped I will sand it with 400 grit paper, wipe with alcohol or lacquer thinner, then wipe with a tack cloth.

As soon as that is done you should apply at least one coat of bare metal primer. Otherwise the metal will start oxidizing.

I then apply 1 or 2 more coats primer, wait 48 hrs then spray Rustoleum color coats.

Spray first 2 coats as directed then sand out any runs with 400 grit wet/ dry. Then spray a final coat of color.

When spraying a frame turn it upside down and spray the bottom side first . Then turn over and spray from the top.

Spraying a frame , it is easy to miss a spot so check carefully after the paint dries for holidays, then spray again if necessary.

I don't use a clear coat over the color because without it it is easy to do touch ups later with the original can of paint.

Enamel takes a while to dry thoroughly. I will keep the frame indoors for a few days then hang it iin the sun for a week before assembling the components. If you have the time let the bike stand as long as possible befor reassembly since even after a few weeks the paint will still not be completely hard. After a couple months it will be hard as nails.

On old Raleighs with decent paint I have used Rustoleum Clear lacquer over the original paint. Sand the paint lightly with 1000 grit wet/dry , wipe down , then spray clear. The frame will look like new.

In general you can spray enamel over cured lacquer with no problem. on 30 year old paint I have no trouble spraying clear lacquer over enamel . On new work the solvent in the lacquer will eat the enamel and ruin it.

On the old Raleigh sport I did a while back I believe the original finish was lacquer.

Spraying lacquer over old lacquer is like magic as the solvent in the new lacquer dissolves into the old lacquer and scratches disappear.

msl109

Thanks - my refinishing has mostly been of guitars, so I'm well acquainted with the advantage of lacquer melting into lacquer, and thought I might lacquer this frame.

Where can you find a sandblast jig that cheaply? I do have a compressor.

JFraz

Primer is not going to pass the fingernail test. Shoot it, then sand it, then lay the base coat.

The only clear you should spray on, it Spraymax 2K clear coat. It's a two part clear (has a hardener), you flip it over, and rupture the internal bladder that releases the second stage. You'll have to use it within 48 hours. I spray one coat, every 15 minutes, at at temp of around 75-80 degrees.

All your problems will be solved with this 2K CLEAR! It's automotive quality clear coat. The same exact stuff they spray in shops, except it's in a can. Don't forget a respirator... it will kill you. lol

Regular spray bomb clear is not 2K. It will never, ever give you the results you are looking for.

capnjonny 

https://www.shop.com/ALLSOURCE+40015...ehUaAjjn8P8HAQ

plus 5 gal bucket


Also Harbor freight has a gun with a small hopper attached .

go to google and type in Cheap sand blast gun and press images.

howellhandmade

Sandblasting takes quite a compressor, not many people have one that flows enough CFM. And open-air blasting is not without problems, not the least of which is giving yourself clean air to breathe. A paper mask is not enough, and silicosis is no joke. If I needed something like a frame blasted I'd take it to a shop. Probably less money, all told. With patience you can get a lot off with chemical strippers.

msl109

Thanks!

msl109

Well, that's scary. I'd prefer to do it myself for the experience, but no, I'd prefer to keep my lungs. Was thinking I'd buy a decent respirator. Not sure if my compressor is powerful enough. Will have to take a look. Appreciate the cautions. Maybe with some good chemical gloves and goggles, I can get away with using aircraft stripper. Also nasty stuff but effective.

(Sad that autocorrect wants to turn goggles into Google's. )

howellhandmade

I'm all for learning, and a decent respirator is good to have even if you're using methylene chloride. But the guys who blast inside a room (or outside) use full hoods with supplied air. Being able to blast is very handy, but at home a cabinet is best, and there are a dozen things that cost money as you get going. I would guess that you could find a shop that would do it for less than the media would cost you. You can blast with a small compressor, you just wind up doing it in burps as your compressor runs out of the 20+ cfm it needs and needs to catch up. I use an 80 gal., 7 1/2 hp twin stage compressor, which you can get at Home Depot, but it does take up space.

BTW, duck tape makes good masking for sandblasting, and you need to have screws in all the holes.

Something that I've used a lot for stripping but not on a bike yet is Mr. Muscle oven cleaner from Ace. I'ts basically lye, so not as bad as some things, but you need to wear heavy rubber gloves.

msl109

Ok, learning is beginning to seem less attractive. And my compressor is nowhere near that large. Think I'm going to try the chemical route and if that frustrates, find a place that will blast it for me. Emailed a couple in the area and have had no response, though.