Topic: paint for alloy

[fishtoft]

Any ideas on repainting alloy parts, e.g caliper bodies, the originals are chemically blacked and I believe some paints can have a bad effect on aluminium.

thanks.

[kghost]

use a good epoxy primer first, You should be good to go then.

If you want them to really stand up to hard use, Powdercoat them.

[ProTeal55]

Powdercoating is the best way to go.
The more you have done at one time , the cheaper it is.

[Uncle Ernie]

I would think you could have aluminium re-anodized.   If you powdercoat, make sure any holes are blocked well !

[Paul]

In relation to getting them re-anodised, I tried this. The anodisers told me that the alluminium (alluminum) was not a suitable grade for anodising. I said to myself." They were done before, why not again?" nothing to loose, got them anodised and ...This is why I am not an anodiser....they came out #$%*, grey and looked like I was told.)
If you powder coat, some parts need the coating removed again where they mate, and things like the brake caliper housing will need the internals to be masked properly (Pain in the ass)
A good "etching" primer followed by good quality paint (from a rattle can) unless you want the expense of paying a spray painter to use 2 Pack or something.

[mylittleho]

make sure the part is CLEAN and use a good etching primer along with a solvent and heat resistant paint like VHT or the like...

You can also forego the etching primer if you have a sand blaster... I used to do bronze and aluminum casting in college.. I always used rattle cans and never had a problem with adhesion. I would clean the part with acetone.. blast it.. hit it with some high pressure air to get off any remaining sand.. (could acetone it again after blasting) then painted it.. came out PERFECT.. each time..

[Geeto67]

most speed shops sell a self levleing caliper paint. Takes a long time to dry but looks great in the end. Other stuff, prep is more important than the paint so make sure you have a clean surface and blast away.

[kghost]

make sure the part is CLEAN and use a good etching primer along with a solvent and heat resistant paint like VHT or the like...

You can also forego the etching primer if you have a sand blaster... I used to do bronze and aluminum casting in college.. I always used rattle cans and never had a problem with adhesion. I would clean the part with acetone.. blast it.. hit it with some high pressure air to get off any remaining sand.. (could acetone it again after blasting) then painted it.. came out PERFECT.. each time..

And how long did it last? Years?

[jvalbuena]

I used VHT caliper paint on my calipers and brake fluid reservoir. Followed the directions and baked them in the oven for a while. They look great and seem to be brake-fluid-proof though I'm being very careful anyway.

[mylittleho]

make sure the part is CLEAN and use a good etching primer along with a solvent and heat resistant paint like VHT or the like...

You can also forego the etching primer if you have a sand blaster... I used to do bronze and aluminum casting in college.. I always used rattle cans and never had a problem with adhesion. I would clean the part with acetone.. blast it.. hit it with some high pressure air to get off any remaining sand.. (could acetone it again after blasting) then painted it.. came out PERFECT.. each time..

And how long did it last? Years

Yeah so far about 4 years... but this (like I said) was a sculpture so of course it isn't subjected to any heat or anything.

You should be able to use ANY spray paint.. just use a high temp clear but make sure the spray paint is compatible with the high temp clear before painting an entire piece.. I do know this method works on car intakes.. I've seen some NICE mustang intakes painted with a regular rattle can and high temp clear... but prep is essential!!!!!

This is duplicolor metallics "chrome" I just blasted the piece with a sandblaster and then sprayed like 2-3 coats and WOW it turned out nice!!!


http://i14.photobucket.com/albums/a324/scottolan/sculp2.jpg


http://i14.photobucket.com/albums/a324/scottolan/sculp1.jpg

[kghost]

The problem is, cheap paint, AKA Rattle can, doesn't last when subjected to harsh environments.

It will last longer with a good substrate such as a etching primer or Epoxy primer. But not as long as a quality paint over same.

The whole point of paint (on a motorcycle for instance) is 1. To protect the metal from corrosion. 2. To improve the appearance or style.

Unfortunately, the rattle can paint over bare aluminum, steel, etc. does a very poor job of protecting the metal from said corrosion. Also the Spray paint does not hold up well to chemical attack. Acids from the road, Brake fluid, Gas, etc.

Spray paint over metal is fine if you keep it indoors. Just doen't hold up in the real world. Do a search on this board. You'll find lots of posts bemoaning the fate of the old "rattlecan" paint job.

In fact, Good ol' Terry in Australia was bemoaning the demise of his VHT painted cases from exposure to Gasoline.

I could go into the chemical differences of spray paint vs. Polyeurathane, enamel, laquer, etc. but the point is cheap paint doesn't last long.

[mylittleho]

Well that is ANY coating.. even powdercoating.. you put enough solvents on it and it will deteriorate..

Nothing like some simple green a toothbrush and RAW aluminum.. or a wire wheel for that matter (btw we don't have road salt and have very little rust to contend with down here)

[Uncle Ernie]

Paul, you're right about the anodising now that I remember. After the colour soak I think they do some kind of process that sort of "seals" the surface to retain colour better, but it also makes it so it doesn't take colour again. I gues I was thinking that another acid soak might open the pores again.
Please excuse my stupidity.

[kghost]

Powdercoating is about the most chemical/abrasion resistant coating you can get.

I should know  I've had to get it off several pieces.

Short of full on Aircraft paint stripper formulated for Poly's you almost can't get it off.

Even if you don't have salt on the roads, unless you live in a very arid (low humidity) environment (like say Tucson, AZ) you will have corrosion.

Almost all places on Earth are now sunjected to industrail polution of one form or another.

Sorry LittleHo, I think perhaps your experience may be a tad limited with regard to paint adhesion.

18 years experience with all types of machinery has proven to me that while a Rattle can paint job can be made to look good, it won't last under use.

Now, if you want to redo it go ahead. If you are inexperienced do a little research. Doing a quality job isn't really rocket science. It just takes a little knowlege and practice.

If you took your car in to have it repaired after an accident would you be happy if they spraved paint over a new metal fender with no primer? I think not.

Would you be happy with rattle can spray paint over a new or repaired metal fender? OF course not.

Sandblasting then forgoing primer because you believe the blasting has magically given the metal adhesive properties? Come on man, All the blasting does is remove the surface coat, contaminates, and rough up the surface.

[750deepsouth]

Terry in Australia was bemoaning the demise of his VHT painted cases from exposure to Gasoline.

I may be wrong, I though he spilt carb cleaning fluid or something like that on his cases.

[kghost]

Maybe......

Thought it was leaking float overflow tubes or lack thereof.....

[mylittleho]

I've seen intakes and engine parts just blasted and painted then cleared.. now this is a EFI stuff so there isn't fuel everywhere... but they WILL hold up to heat, roadsalts, occasional spills of fuel, oil, etc.. but bike parts are 100% different.. they tend to leak, spill, get doused with everything under the sun more frequently... like I said though.. to me clean raw aluminum is a pretty sight

[kghost]

Love it when polished..............

Just have to keep polishing and polishing, during and after.

[ProTeal55]

If you are going for the raw alumn. look , here's a way to get the look you want , and not have to clean it every 5min to keep it up....

1. Have the part sandblasted
2. Have the part Ceramic coated Silver
3. Take a scotch-brite pad and go to town , making sure all sanding is done in one motion

The final look will be of clean , raw alumn, yet the cermaic coating will keep it looking good for years.
Russel Mitchell of Exile Cycles kinda of started this trend , to have the look of raw metal on his bikes , yet have the look last in everyday use...

[cbjunkie]

Proteal,
Sorry to bust in - I'm curious about your bars and seat - do you have better pics of your bike posted somewhere?

johnny...

[mylittleho]

Love it when polished..............

Just have to keep polishing and polishing, during and after.

After working around aluminum I like mixed polished and raw finish.. for the raw finish.. I just take a bronze wire wheel on a right angle grinder and go to town... still a raw finish but it gives a nice sheen to it... for polishing.. I HATE HAND POLISHING.. it's nothing but white tripoli or finishing compound put on by a 6" loose sewn wheel on a 6,000 rpm air die grinder... just have to mask/tape things that might get hit with flying compound...

[ProTeal55]

CBJUNKIE ----->

Shoot me an email at Joe@Americasopenroad.com
I have a few other pics of my bike I can send ya....

[cbjunkie]

joe - pm incoming

[ProTeal55]

The look of raw alum. can not be beat , in my opinion.
If it isn't raw , then it should be black.
The Ceramic coat / Scotch-Brite method will give you the look of raw metal , without the hassles...

[fishtoft]

Many thanks to all for suggestions, will go down the Primer/paint route seems pretty simple.