sylvierose

Hey everyone,

I am trying to do up by girlfriend bicycle, it's like a Raleigh 20 style 18" Morrison, and I've had some trouble with doing a final gloss coat.

I sanded the frame down primed it and spray painted it green (with Montana spray paint) but when I used the acrylic gloss I'd bought (of a different brand to the spray paint which is where I think I went wrong!) the green underneath began rising up into tiny little wrinkles, reacting with the overcoat in some way.

I was wondering if to remedy this I will have to strip all the paint off back down to the metal and start over (I hope not!) or if I can just do a vigorous sanding job and reapply the green?

Help much appreciated!

Jeff Wills

Your paints are fundamentally incompatible. You need to start over from bare metal and use compatible paints from bottom to top. The second easiest way to do this is buy paints from the same manufacturer, and then verify that they're compatible before spraying the frame. The easiest way to get where you're going is to take the frame and fork to a powder-coater: https://bikeportland.org/2009/02/04/b...ur-bike-video/

BCRider

Except that I have yet to see a truly glossy powdercoating job.

The top solution would be to have an autobody shop do it during a quiet time. They'd use a "base clear" system of dull color topped with a two part polyurethane clear coat. The results are actually very durable once it's dried and cured for about a week to ten days. The downside is that it's going to cost ya a cool C note or more to get the job done even if you bring it in all stripped and preped.

sylvierose

Well my primer and body colour are definitely compatible, it is just the gloss coat. What I was trying to ask is whether I can sand off the gloss coat without having to go as far as paint stripper etcetera for the layers underneath. After that I hope to reapply a green and a gloss coat which is compatible with the green. This is the first bike I've painted and is kind of a practice - I am not too concerned about getting pristine results, just a smooth[ish] finish...

BCRider

Nope, the alligator skin effect that lifted the color up has broken the bonds and ruined it to at least the primer. It's a start again deal for you. Sand or strip is your choice. But it's a LOT easier to strip it and start again.

Jeff Wills

BC beat me to it... you have to go all the way to bare metal. The solvents in the gloss coat have attacked the lower coats. Ain't nothing going to "fix" it- you have to start over. Been there, done that, inhaled too many paint fumes. *Cough*.

liverpool pete

test the paints out on a pipe first next time ,it's most probably cellulose based clear coat and it's reacted .
unfortunately it's like the others said it's a strip start over.
i have had good results with a paint called hammerite smooth gloss, there's no need to under coat and it will cure any rust .

DannoXYZ 

General rule-of-thumb with paints is to never lay fast-drying paints on top of slow-drying paints. However, the reverse is perfectly fine, laying slow-drying paints on top of fast-drying ones. Acrylics and lacquers are fast drying and can be used as base coats. Enamels and polyurethanes are slower drying and can be used as top an clear-coats.

At this point, you need to remove all of the paint down to bare-metal and start over. The acrylic gloss has chemically mixed with the underlying layers. So even if you were to sand it off, there's still traces of it in the underlying layers that will react badly with any new paint you apply.

ultraman6970

haha thats funny I feel sad for you in a good way ok? I'm just smiling now

Have no idea what type of paint the montana is but for sure the clear coat you put in there was a darn lacquer. Ask the guys from montana what type of paint is, i bet is a water based acrylic type of paint, then you put the clear that im 10000% sure it was a lacquer then the clear started eating the paint underneath big time after 10 to 20 minutes . Looks like the montana paint is a rebadge of another brand hmm something like plutonium? cant remember.

Next time use this... use u-pol clear coat, that clear is polyurethane it should not affect the paint you are using at all.

Now u have to sand again and start over, my advice is to go to the car paint shop and get paint in there, get u-pol primer or any other can car primer then ask them for polyurethane paint and get the smaller can of thinner for that paint, the paint and the thinner need to match or you are asking for trouble again, and no mineral spirits or water wont work . If you do not have a spray gun or a compressor, neither a hobby spraybrush thingy ask the guy to put the paint in cans for you and get at least 4 to play safe. Buy a good mask also because that paint stinks and is super toxic. Apply the primer... paint... let dry for 30 minutes... paint again... then done. Let it dry for at least 3 hours and sand if needed. Then apply the upol clearcoat twice and let it dry. If you need to sand do so. polish the paint. Done.


Paint is not just go ahead and do it, the main problem with all those canned products is that wont stand the usage of the bike and probably you will start getting chips and nicks in the paint while putting the parts back in the bike. The main issue is that the acrylic laquer takes centuries to cure, and we are talking about 6 months for that to happen. A polyurethane paint will take a while to get fully cured but at least you an use it almost next day w/o having problems. That the paint is hard and that you can touch it doesnt means that is cured.

Good luck again, probably will be faster and cheaper for you get a 100 bucks powder coating job. Or a friend that paint cars.

Good luck

fietsbob

go for one type of paint , a gloss enamel as the color coat, and leave it at that.
not real tough stuff but, their advantage is touch-ups will be easily done

Polyester powder coat melts on the metal to a decent shine, Its a plastic glazing

Ive tried epoxy powder too, tougher stuff, but the melt suface characteristic is kind of orange peel. at least on my sample.

KDC1956

Best way is to start all over but I would use auto paint and get the harden for it.That way you can mix the harden in with the paint and do a two coat and you will have a nice looking bicycle.I hope you have a good spray gun to work with if not have a auto body shop to do it for you.Spray painting is very easy to do with the right stuff on hand.I have painted a lot of cars and an old time Model T car.Its fun to do it your self you can give it a whole new look if you have a spray gun and a air brush it can even be better than what came on it if you do it the right way and have a very nice ride for her.One she can say my BF did this for me.But do it the wrong way and she will not like it at all lol.And say look what he did to my bicycle.

ultraman6970

KDC the problem he wil have is that the hardener for car paint is super expensive and probably they wont sell him a pint or maybe a quarter of it, that thing at least here is for the gallon and buy a 150 bucks hardener is not cheap at all, specially if you do not paint cars. Besides if he mix the hardener, the paint and the thinner wrong it means to ask for troubles.

You can paint using car paint w/o using hardener, but you need the thinner and a good clear coat. You can buy thinner in quaters just in case and is relatively cheap.

God luck OP

DannoXYZ 

Don't get activators and reducers mixed up. They are different things and both are required.

KDC1956

Its only money guess I buy what I want and don't worry how much I spend.I can't take my money with me when its my time to go so I use it as I get it now lol.But I do understand some places do charge way to much for auto paint and all stuff do add up fast.I just do as I want now days it even makes my wife mad at me sometimes too lol.Besides hobbies are not cheap.

ultraman6970

Painting bikes in general is not cheap at all hehehe In a matter of fact im still learning My paint jobs still suck Darn car paint is so expensive from 20 bucks a pint to over 100 the pint but the difference is heaven to earth type...

Nah the hardener is not necesary u can just paint using the thinner, just have to leave the frame drying for 3 days before start touching it and sanding the imperfections. At least under my experience u can leave the hardener out, but thinner is mandatory or you will clog the gun right away

DannoXYZ 

Depends upon the paint composition. Two-part epoxy paints or polyurethanes will remain gooey and runny forever without the activator. Adding just the reducer makes it thinner and easier to spray on a smooth layer, but it will never cure and harden. Of the two parts, only the reducer is optional. Lacquers only need thinner, but those aren't good paints for bikes or parts that experience flexing.

I've sprayed Glasuri, DuPont, PPG on cars, motorcycle and bikes for the past 30-years. Look up the manufacturer's specs on what each paint needs. Each composition is different.

DannoXYZ 

The Omni AU line is a great paint for the money. About $40 will buy you a pint of paint, activators and reducers. That's enough paint for 5-10 bikes. So it's actually more cost-effective than rattle-cans. And give you better finished product as well.

sylvierose

Hey everyone,

thanks for all your help. I've re-sanded the bike down to the metal and bought compatible kinds of primer, paint and gloss coat which I have reapplied. I just got hardware store stuff, not auto paint or anything... this is a cheap amateur job but to be honest the bike is looking pretty sweet! And for everyone who is referring to me as a 'he', I am a girl, I think the name sylvierose implies that ... so in future don't just assume someone who has a girlfriend is automatically a dude!

Thanks again for all the advice, I think my girlfriend's going to like it.

ultraman6970

Lost trace of this one... well forgot to add this : the cheappo urethane paint can be sprayed only with thinner (I have done it, and looks ok but not even close to the good stuff, but it works), after all there is a big difference between a 10 bucks pint and a 120 bucks pint of urethane paint. And yes i agree with you that with the expensive stuff u need the whole shabang danno.

BCRider

Slyvierose, if you can spare the time and have the patience let that frame dry for a good week to two weeks. ANY paint takes a LONG time to actualy gas off all the solvents and achieve maximum hardness. It may be dry to the touch the next day but it'll be very soft and scratch prone. Let the same paint dry untouched for a week to two weeks and it'll be a LOT tougher, scratch resistant and less prone to chip off from contact pressure as the parts are re-installed.