weekend project

[E30 325i Rag-Top 2956]

Good description on the process for painting the wheels, makes the car stand out a bit from the crowd.

From my experience the "quality" of most paint jobs is down to the preparation, you can paint with the best materials in the best pattern over sh!t prep work and it will still look like sh!t! The hours can build up in the prep work very quickly and that is where a lot of the cost builds up on a great paint job - the man hours soon rack up.

Using a blast media is a good way of saving time and getting a better prep, it is unlikely most people will have a media blaster around so to avoid paying to have it done, will go with the DIY sanding option. Personally I would suggest paying for the blasting, especially on rims as they are exposed to pretty harsh treatment so the paint can suffer.

I appreciate you were spraying in what looks like your garage, but to get best results with a clear coat bake it afterwards, this promotes the reaction between the two layers to get them to key together fully and stop the clear coat lifting off later on.

[bellicose 9]

but to get best results with a clear coat bake it afterwards, this promotes the reaction between the two layers to get them to key together fully and stop the clear coat lifting off later on.

Jon, i know what you're trying to say but i'm sorry it's BS.

I have NEVER had a de-lamination issue with anything i've painted, whether it's done in a heated booth or a backyard shed.

Heated booths ("bake ovens") are to speed up the process of getting the job done ie 'turnaround' and has nothing at all to do with the curing of the product, or as you say "promotes the reaction"

2 pack uses a chemical reation to cure NOT heat.

The only time you will see clear lifting off (de-laminating) is if the painter has missed his clearing window (the time between colour 'flash off' and the allowable max' time before clear) or the use of products that are not compatible ie: Acrylic lacquer colour and 2 pack clear.

Edited June 22, 2011 by Westy

[E30 325i Rag-Top 2956]

Heated booths ("bake ovens") are to speed up the process of getting the job done ie 'turnaround' and has nothing at all to do with the curing of the product, or as you say "promotes the reaction"

2 pack uses a chemical reation to cure NOT heat.

Whilst I still do not fully understand all the chemistry involved, my understanding of the base-coat / clear-coat systems I am working with is that there are two distinct reactions occurring at pretty much the same time.

The first is the 2-pack reaction with the iso-cyanate hardener curing the basecoat (and also into the clearcoat), there is a seperate reaction between the base-coat and the clear coat which creates a bond or cross-linking of elements in each of the two materials (they knit together in effect). This will only occurr at 50+ degrees C, no matter how long you leave it to dry (with PPG product anyways).

You are correct, in the real world a total de-lamination is not going to happen unless something else has been done incorrectly, like you say the basecoat has been allowed to fully cure before the basecoat is put on. However, in the extreme cross hatch testing with heat cycling, UV cycling and moisture exposure tests that we need to meet for the OEMs the lack of baking will produce negative results, but again, not total failure of the clear coat.

With the heat, brake dust, etc. that rims get thrown at them I thought it best to use the paint system to the fullest. However, it is possible that different basecoat / clearcoat systems work in a different way, although the three or four systems I have looked into & had tested were pretty similar from that respect.

[bellicose 9]

UV cycling and moisture exposure tests that we need to meet for the OEMs the lack of baking will produce negative results, but again, not total failure of the clear coat.

To start let me say, i unfortunately think you may know a little more 'bout this than me, sh*t it's hard to be humble

Secondly, when you say "we" in the above statement, does that mean you're a chemist or in the paint / refinish industry?

If so i'd like to talk to you some more.

[E30 325i Rag-Top 2956]

To start let me say, i unfortunately think you may know a little more 'bout this than me, sh*t it's hard to be humble

Secondly, when you say "we" in the above statement, does that mean you're a chemist or in the paint / refinish industry?

If so i'd like to talk to you some more.

It's one thing to know the chemistry and theory, but I can't paint for sh!t! I leave that to people with the right skills. My job is to make sure the right stuff gets put on in the right way, far easier than the actual spraying.

The company I work for supply painted and assembled parts to the car manufacturers in Aussie, HSV, Holden, Toyota, Mitsubishi, etc. We have our own, small scale paint shop here in NZ, and use a couple of sub-contractors in Aussie, which I have to try and keep under control. I spend a fair bit of time working with the paint suppliers and the car manufacturers to make sure the stuff is going to stay on for 10 years and a million kms!! Drop me a PM and we can talk, no worries.

[westy 614]

It's one thing to know the chemistry and theory, but I can't paint for sh!t! I leave that to people with the right skills. My job is to make sure the right stuff gets put on in the right way, far easier than the actual spraying.

The company I work for supply painted and assembled parts to the car manufacturers in Aussie, HSV, Holden, Toyota, Mitsubishi, etc. We have our own, small scale paint shop here in NZ, and use a couple of sub-contractors in Aussie, which I have to try and keep under control. I spend a fair bit of time working with the paint suppliers and the car manufacturers to make sure the stuff is going to stay on for 10 years and a million kms!! Drop me a PM and we can talk, no worries.

Wait, what?

We still manufacture something?

[e38king 1]

To start let me say, i unfortunately think you may know a little more 'bout this than me, sh*t it's hard to be humble

Wait, what?

Humble pie?

[E30 325i Rag-Top 2956]

Wait, what?

We still manufacture something?

Ssshhh, don't tell anyone it's a secret

[gpetersen 0]

hahaha take it easy guys, its just a wheel painting thread yeah i cudv/ was thinking bout getting them sodablasted, but didnt. I get them stripped and paint them standard colour if i sell the wheels or the car to make it more sale-able.