A Forum Project; Testing Car Paint & Anti Rust Treatments

[Ross365]

This a great idea...or a daft idea. In the past, various car magazines have done tests where they have painted bits of metal with various products, left them out in the rain for a long time and reported back that Product A is great and Product Z is rubbish. Unless they had someone on the team who knew a bit about corrosion testing, I'd tend to be wary of the findings.

I've always wanted to do my own tests, and I have, but only two "combinations of products" but the results were useful and showed A definitely better than B.

I trusted my results because I spent a large part of my professional life working on corrosion, though not specifically on paints. In terms of working on rusty cars, I've been at that for over 40 years.

Anybody interested in forming a little team to do some tests, and, try and do them in a professional way?

 

[dyno-tron]

I recently took the plunge and bought some evaporust and found that it does exactly what it says so I can join in with this. I’ve done electrolysis, vinegar, molasses, citric in the past and been variably dissatisfied with the results and the amount of faff especially with electrolysis. Each to their own but a clear list with “this works but expensive” “this is cheap and effective but…..” etc etc would be handy.

 

[Mick Annick]

This a great idea...or a daft idea. In the past, various car magazines have done tests where they have painted bits of metal with various products, left them out in the rain for a long time and reported back that Product A is great and Product Z is rubbish. Unless they had someone on the team who knew a bit about corrosion testing, I'd tend to be wary of the findings.

I've always wanted to do my own tests, and I have, but only two "combinations of products" but the results were useful and showed A definitely better than B.

I trusted my results because I spent a large part of my professional life working on corrosion, though not specifically on paints. In terms of working on rusty cars, I've been at that for over 40 years.

Anybody interested in forming a little team to do some tests, and, try and do them in a professional way?

I’m rubbish at doing anything properly, but would be happy to sponsor the tests.

 

[bricol]

Some ideas for testing setups, as used for cavity wax and rust prevention coatings -

https://www.auson.se/wp-content/uploads/2020/03/rusttest_noxudol_700_classic_monthly_uk_1.pdf

The results persuaded me to use the noxudol stuff.

 

[OJCar]

I can supply plenty of rusty things to be tested.

 

[Ross365]

The stuff the mags have done previously are certainly well worth looking at. But I'd want to find what the internationally accepted test methods are, so BS in the UK, DIN in Germany and ASTM in the States. Often, ASTM (American Society for Testing and Materials) attains an International acceptance. Those guys charge quite a lot of $ just for their procedures. Any one got "access to them" ? It may not be possible to conform exactly to the standard tests, but we'd do the best we could.

I'll tell you about the tests which I did. I'm on record on the forum of being a big fan of zinc phosphate primers. A mate of mine said he found this product which was some kind of "phosphating agent" to be used before painting and that it was damn good. Without going in to too much detail, I prepared 4 specimens (mild steel);
2 got the magic product and then the zinc phosphate and
2 the zinc phosphate alone.

I think it's best that I don't name products in this case where only I did/saw the tests.

Neither got top coats as I wanted to speed things up. Long story short, the specimens with the 2 product surfaces showed rusting after about a year, when the one product still looked good. Now, those tests certainly didn't conform to any standard test methods (I regretted that afterwards) but they were back-to-back tests and the results were (I believe) unambiguous. If there's somebody on the forum who's been involved in paint testing that would be great.

 

[Parm]

I believe @Wightsparks did something similar a while back?

Haven’t seen him on here for a while

 

[Keithmac]

"Project Farm" on YouTube is worth a look, he's done quite a few anti corrosion product tests and he's very thorough.

 

[cr500dom]

I recently took the plunge and bought some evaporust and found that it does exactly what it says so I can join in with this. I’ve done electrolysis, vinegar, molasses, citric in the past and been variably dissatisfied with the results and the amount of faff especially with electrolysis. Each to their own but a clear list with “this works but expensive” “this is cheap and effective but…..” etc etc would be handy.

Yep, I concur with this too.
Evaporust in my experience is easier and a better result than citric acid for sure, and no risk to cast iron unlike citric (which I did manage to ruin a few bits with after prolonged exposure)
.
Most industry tests are salt spray as it’s the harshest environment
You need the salts and then the oxygen to create the corrosion
Splash zone on offshore structures is always the harshest test for paints and coatings.

 

[steveo3002]

Some ideas for testing setups, as used for cavity wax and rust prevention coatings -

https://www.auson.se/wp-content/uploads/2020/03/rusttest_noxudol_700_classic_monthly_uk_1.pdf

The results persuaded me to use the noxudol stuff.

hard to believe waxoyl is really the 2nd best cavity wax , you have to wonder if these are sponsored tests or something ...no mention of the lanolin treatments or acf50 and the like

 

[bricol]

hard to believe waxoyl is really the 2nd best cavity wax , you have to wonder if these are sponsored tests or something ...no mention of the lanolin treatments or acf50 and the like

I don't - I've been reasonably regularly blowing it into a 1991 Pug 106 of dubious parentage that I've owned for 20 yrs - its stood outside all the that time, got washed once by accident by a girlfriend (now ex), used in off-road trials, winter, has got a leak into it from somewhere I can't trace, etc etc - sills, rear arches, floor, and most of the front (where I did apply it) are still original with no signs of distress.

If you look at the date - that was way before the lanolin people staring throwing posts all over face book.

The key to all these treatments is regularly reapplying.

I believe Noxudol is now used/authorised by Nissan in the USA as something to stave off the chassis snapping antics of their pickups from rust. The data sheets for it show it contains preservatives, rust convertors etc. I'll let you now in a decade or so how it's done.

 

[Ross365]

Yep, I concur with this too.
Evaporust in my experience is easier and a better result than citric acid for sure, and no risk to cast iron unlike citric (which I did manage to ruin a few bits with after prolonged exposure)
.
Most industry tests are salt spray as it’s the harshest environment
You need the salts and then the oxygen to create the corrosion
Splash zone on offshore structures is always the harshest test for paints and coatings.

Could you say more about the problem of cast iron with citric - I'm not aware of that? The interesting thing about a product like Evaporust is that for very little money (~£400) you could get it chemically analysed. I've had other automotive products analysed on behalf of a client.

Yes, the salt spay test is widely used. Of course the other trick to get data faster (i.e. "accelerated" testing) is to test at higher temperatures. There's a rule of thumb that does seem to work a lot of the time; increasing T by 10'C doubles your rates. But it is something of a gamble. I know of some compatibility tests done on rubber at 20, 40 and 60'C. The damage done at 40' was indeed 4x that at 20', but up at 60' spooky stuff was happening and the damage done was completely off the scale.

In the same way, I wonder how realistic is to use prolonged salt-spray testing in a study intended to apply to cars in the UK? And I guess the average car in Scotland see's much more salt than a car in southern England?

So for a test of paints to be used on cars, I wouldn't want to go above 40'C and I'd want to limit the extent to which salt spay was involved. But I don't know for sure what any of the Standard Tests call for.

 

[OJCar]

I guess the average car in Scotland see's much more salt than a car in southern England?

Off a ten year old Scottish Skoda Octavia.

 

[steveo3002]

could you get hold of whats actually put on the roads ? strong with mix wet mud and bury it would be realistic , stuck in thick mud nov - march , jet wash off in april equals road conditions

 

[Keith 66]

My son works as a test engineer, he tells me that they use a considerable range of standard muds & salt solutions to replicate where an item is going to be used. Its isnt just any mud you know!

 

[Dcal]

If it's a comparative test does the method of accelerating the corrosion really matter?
I think speeding the test up is a given or it would be pointless for us old codgers, but I suppose the younger members could benefit.

I'd be happy to be involved but where are the goal posts.
Does someone send samples of the same materials to those who want to participate, then the members prep and paint the coupons with their favoured system and send them back for testing?
It will to be hard to get any valid results without using the same base materials and the same test environment.

I have some 0.8 mild steel with a good coating of surface rust I could cut to size and send to anyone who wants to participate however we need to set the ground rules first.

I could do epoxy mastic (Jotamastic 90 because I have it)

I'd suggest differient prep but the same number and thickness of coats recommend for the chosen system for example

One sample with no prep but with two coats of Jotamastic then top coat.

One with the wrong mechanical prep (high speed wire brush) same paint system.

One with proper mechanical prep (st3) and same paint system.

One blasted to sa2.5 and same paint system.

One blasted to sa2.5 and only one primer and top coat.

The back side could be left bare and coated with differient types of wax to test the complete package.

I found a very nice test setup on YouTube, where a test rig dipped the samples in salt water then brought them out and took a photo, but can't find it.

If you use differient base materials you will probably get differient results. For example, some new steel will rust less than some recycled and new steel will certainly rust less than old rusty steel that has road salt trapped in the bottom of rust pits, even if they are both blasted to sa2.5.

 

[addjunkie]

By the time youve all figured this out my defender will be a pile of reddy brown flakes on the drive!

 

[Ross365]

If it's a comparative test does the method of accelerating the corrosion really matter?
I think speeding the test up is a given or it would be pointless for us old codgers, but I suppose the younger members could benefit.

I'd be happy to be involved but where are the goal posts.
Does someone send samples of the same materials to those who want to participate, then the members prep and paint the coupons with their favoured system and send them back for testing?
It will to be hard to get any valid results without using the same base materials and the same test environment.

I have some 0.8 mild steel with a good coating of surface rust I could cut to size and send to anyone who wants to participate however we need to set the ground rules first. I found a very nice test setup on YouTube, where a test rig dipped the samples in salt water then brought them out and took a photo, but can't find it.

If you use differient base materials you will probably get differient results. For example, some new steel will rust less than some recycled and new steel will certainly rust less than old rusty steel that has road salt trapped in the bottom of rust pits, even if they are both blasted to sa2.5.

Well yes, if this worth doing, it's going take some time (maybe a month?) to sort it. I'd say we need one commons source of test samples, and as Dcal suggests;

I have some 0.8 mild steel with a good coating of surface rust I could cut to size and send to anyone who wants to participate

One with the wrong mechanical prep (high speed wire brush) same paint system.
One with proper mechanical prep (st3) and same paint system.
One blasted to sa2.5 and same paint system.

Actually, I'd prefer duplicate tests, even if the test coupons have to be smaller?

This looks like the core of a project; something that starts rusty, generating some specimens partially de-rusted and some specimens fully de-rusted.

I guess that what then goes on top of those specimens is up to individual participants.

We need to consider one other issue; who owns the data and what we going do with it? It may be sellable a car mag, bit I doubt if we are talking more than a couple of hundred quid? However, let's agree it up front.

 

[Trevorleach]

By the time youve all figured this out my defender will be a pile of reddy brown flakes on the drive!

It already is, it is just you cannot accept the truth