How to repair pitting?

[joey]

I've bought a set of gt bonnet vents for my ta22, whilst they are still in the process of being posted i wanted to know about how i would fix the surface pitting on them. I have access to a professional bead blaster, can this be used to get rid of it or is it just a matter of sanding it back?


As you can see they are in pretty average nick and would need to be re-chromed and re-touched in black so has anyone got any large close up pics of them so i can figure out the detail of where the black is applied?

Any help is greatly appreciated. Cheers, Joey

[skiddz]

basically they are cast rat shit.... i mean aluminium, so it is very hard to get a good finish on em (when chrome plateing) basically id just take em to a plater and say here, hand over 2-300 bucks and wait a few weeks. the reason this costs so much is because ALOT of copper is needed to iron out the inconsitencies that are present in a cast rat shit part, that and the price of copper is higher than gold.... so why dont you gold plate em bling FTW

basically take them as is to the plater and he/she will sort out the cleaning up n shit of em

edit* oh just thought i would add, that "pitting" comming through is oxidisation of the aluminium underneith the chrome not the chome itself, also make sure they triple plate em, copper then nickel then chromium, lasts longer, looks better

[joey]

Thanks skiddz, i was expecting "they are ghey" . however is there anyway that i can get rid of the pitting myself to save the cost (which will be double the price for what i paid for em )

[skiddz]

well they are ghey lol

ummm the way i know to strip chome is with a sodium hyrdoxide/sodium carbonate electrolysis bath.... and that would destroy the aluminum i suppose the only way to do it is file/ grind or wire wheel and sand it..... i would file rather than grind cos grinding leaves big fuck-off marks, id buy a wire wheel/ flap disc and have a crack but go really slowly id hate for you to destroy a set of these

[EldarO]

sand paper FTW.

320 grit looks like it should get most of the shit (chrome plating) off, if it doesnt budge it, 180 grit will.

use a sanding block and you should get it nice and flat, just dont rush it.

Elmo.

[joey]

Will the pitting come back tho? i.e like rust, will sanding it back just prolong the process and will re-accur.

[Sigmeister]

If you got the linished, wouldn't that get rid of the pitting? Should cost too much to get that done?

[shelldrake]

Joey, Pitting in these parts is hard to get rid off indefinitely. For the money you would spend getting them all nice and chromed perfectly, I would say you are far better off to sand/smooth them out with s/paper. fill any imperfections with filler. Then paint them/powdercoat them in high metalic silver. It will still look awesome and cost you 200 or so less.

Do not sandblast them, they will prolly dissolve in front of your very eyes. Try a door handle or some other cast part first and see how that goes being blasted.

BTW I have some side vents for you. pm me if you are interested.

[joey]

isn't getting something "linished" the equal of a finish by 320 grit paper? (sourced this info from google so it many not be right).

BTW i can get them chrome plated for free (or for basically nothing) so it's just a matter of sorting out the pitting.

[EldarO]

id just sand as much as you could off, then spray it with spray putty.

the thickness of the putty will fill the pits, and after you sand it back and re-apply a couple of times, it'll fill the pitting, seal it properly, and stop it happening for a fair while to come.

i mean, think about it... how old are those vents? are you going to still own the car in that amount of years? and is is economically viable to re-do it then?

Elmo.

[skiddz]

if you are getting them rechromed dont paint them

also if you are getting them chromed donot use filler

also there is very little one can do to stop cast aluminium from oxidsing a good plater can make it go away for a long time but it will come back

edit, if ur getting em chromed for free rub the feckers back, and if there are any small imperfections after this the plating proceedure will take care of this, ill say again DONT PAINT OR FILL!!! thats what the copper is for

[EldarO]

Then paint them/powdercoat them in high metalic silver. It will still look awesome and cost you 200 or so less.

i was referring to that option.... thus the filler suggestion

Elmo.

[joey]

Ok, well just sanding it back looks like the option for me, would i need to use one of those wet sand papers in the finishing process to stop the chrome from showing the scratch marks, or is it not that precise?. also quickly, anyone know if the "insides" of the vents are supposed to be all back or chromed on the raised curves?

[skiddz]

i wouldnt go any finer than 400

id make those bits black, could look quite hawt, the whole object is gonna get coated so you may as well prep the whole lot and

[thechuckster]

old-skool suggestion:
-soak/wet in brake fluid for days at a time
-hose off with moderate/high pressure
-repeat as required

cast aluminium is softer than some paints so once you leave grinding marks, they're there permanently.

you could try testing various paint strippers on the rear of the item but it's most likely that any highly caustic junk will attack the metal.

There's some fine detail around the outer edges of the vents (having seen a set up here) that seem to get full of paint & filler so if you sand it back till you see bare metal, you'll loose stuff.