Aluminium oxide grade for stubborn powder coat....

[Lew_boi]

Currently using 120 alu oxide to blast alloy wheels after chemical dip before powder coating but have come up against 2 set this week with a base coat I cannot shift (cheaper after market wheels). Next step is to try courser media.
What grade are people using ?
Don't want go too harsh and mark the alloy.
Thanks, Lew

 

[rtbcomp]

Welcome to the club!

What is the chemical dip you use at present?

There's some stuff on the market called Atlas-T, it's produced by Eurochem Northern Ltd, not far from you. It'll shift anything.

Personally I wouldn't switch to a coarser grade of grit, you'll gouge the ally and leave a finish that requires a lot of building up with primer &c.

 

[Lew_boi]

it's Atlas T I'm using ! Read afew bits on various sites about some aftermarket wheels made mainly in the Far East using very strong etch primers... Top coat came off in minutes but left a thick base coat.
Stripper definitely weakens it but still not enough to blast it off.....
How long do you generally leave alloy in for ?
Poly powder I can strip in 40mins or less, paints in 10-15.... These have been in for hours and not budging !?!

 

[rtbcomp]

I refuse to do them.

It took me a full day to do one wheel once.

 

[Lew_boi]

It's looking like I may have to do the same....
I've only recently got started so everydays a school day ! Luckily 1 set's mine from around 10 years ago and the other is a mates spare set. I'll have to get his done but times not really an issue.

 

[rtbcomp]

One problem with Atlas-T is that it contains hydroflouric acid and it works by removing a thin layer of metal, taking the coating with it. If you get a patch where the coating comes off easily the exposed metal can end up being corroded.

It may be better to use methylene dichloride (dichloromethane), which is organic and doesn't attack metal, and soak for a couple of days. You need to cover the bath with water to prevent it from evaporating.

 

[Chris Stevens]

Currently using 120 alu oxide to blast alloy wheels after chemical dip before powder coating but have come up against 2 set this week with a base coat I cannot shift (cheaper after market wheels). Next step is to try courser media.
What grade are people using ?
Don't want go too harsh and mark the alloy.
Thanks, Lew

I have dealings with a very big commercial wheel refinishing concern, I will ask what they use next time they want something doing.