jimllshiftit · Tuesday at 12:20

Theres a galvanized chassis and bulkhead sitting outside my workshop at the moment waiting to be decorated with the components from my very rusty 90 but i keep reading and hearing conflicting information regarding how to prepare it for paint.

Rather than relay the information ive received to you experienced folk could you share that experience with me please?

The components are as follows:

Shielder 200 tdi bulkhead. Delivered about a month ago and has been sitting outside since then. Galv is still shiny.

Shielder 90 chassis. Has been here outside for 18 months. Galv is still fairly shiny but not completely dull as galv becomes in time.

Also I have some galvanised body cappings that were galvanised a few years ago and are now as dull as galv can get.

I want to paint the chassis in matt black and the bulkhead and body cappings will eventually be Epsom green metallic, but i want to make sure i get the process right in order to avoid it all falling off the galv as ive read in other horror stories.

Looking forward to reading what youve all done with your galvanised bits.

dag019 · Tuesday at 12:48

jimllshiftit said:
Theres a galvanized chassis and bulkhead sitting outside my workshop at the moment waiting to be decorated with the components from my very rusty 90 but i keep reading and hearing conflicting information regarding how to prepare it for paint.

Rather than relay the information ive received to you experienced folk could you share that experience with me please?

The components are as follows:

Shielder 200 tdi bulkhead. Delivered about a month ago and has been sitting outside since then. Galv is still shiny.

Shielder 90 chassis. Has been here outside for 18 months. Galv is still fairly shiny but not completely dull as galv becomes in time.

Also I have some galvanised body cappings that were galvanised a few years ago and are now as dull as galv can get.

I want to paint the chassis in matt black and the bulkhead and body cappings will eventually be Epsom green metallic, but i want to make sure i get the process right in order to avoid it all falling off the galv as ive read in other horror stories.

Looking forward to reading what youve all done with your galvanised bits.

I have done bulkheads, chassis and lots of galvanised brackets from YRM. The technique and order I use is:
T-wash
Primer
Topcoat
Dintrol

The primer I use depends on the applications and part, I use an acid etch primer for body panels, and Zinc 182 for everything else.
The choice of topcoat depends on the part and application, all my body panels are in coach enamel, all my chassis brackets are in machine/tractor enamel, chassis was corroless glass reinforced
Dinitrol again depends on application, 3125 HS for internal cavity (doors, bulkhead, chassis etc) and 4941 for external (this goes on everything other than body panels before fitting)

you can see some of these process is my threads here:
station agon body rebuild,
rebuild after fire,
dinitrol discussion

landowner · Tuesday at 13:38

Patio cleaner to etch and then paint

jimllshiftit · Tuesday at 15:27

And so the plot thickens

Thats not the first time I've heard patio cleaner (muriatic acid) be suggested.

Can T wash be used on old galvanized steel though? I've read that it should only be used new shiny galv.

What about keying the surface? Should it be scuffed up before T wash?

landowner · Tuesday at 16:23

I did my full new galv chassis with patio cleaner in a kitchen spray.
Washed it off and did it again
Dulled the shine off it ready for paint
Painted in black gutter paint and still good when I sold it years later

meego · Tuesday at 17:10

jimllshiftit said:
And so the plot thickens

Thats not the first time I've heard patio cleaner (muriatic acid) be suggested.

Can T wash be used on old galvanized steel though? I've read that it should only be used new shiny galv.

What about keying the surface? Should it be scuffed up before T wash?

I would still use T Wash if it was mine. You are correct in saying it is usually for new galv though. I have seen paint just peeling off in sheets from unprepared new galv in the past, as it has nothing to grip on to. It’s not worth the hassle not to use it in my opinion. Never heard of patio cleaner being used before.

dag019 · Tuesday at 17:22

jimllshiftit said:
What about keying the surface? Should it be scuffed up before T wash?

No need to key the surface as it is a chemical reaction rather than needing to adhere to the surface like paint.

meego said:
I would still use T Wash if it was mine. You are correct in saying it is usually for new galv though. I have seen paint just peeling off in sheets from unprepared new galv in the past, as it has nothing to grip on to. It’s not worth the hassle not to use it in my opinion. Never heard of patio cleaner being used before.

This^^ I completely agree with. For the price and ease it is not worth the risk of not using it in my opinion.

In terms of patio cleaner vs t-wash i have not bothered to look into the chemistry behind it so do not know which is better. but t-wash is designed specifically for the job which is why it is my preference. Patio cleaner is about half the price, but the 2.5l of t-wash I bought years ago is still going strong, you use far less of it than you do paint. I am also of the feeling that as prep is the most important art of a paint job it is not an area I want to be penny pinching, and with the price of quality primer and paint these days what is another £10 (quick google price difference on 5litres) to use t-wash?

jimllshiftit · Tuesday at 18:24

Saying this from only a basic understanding of metallurgy I have no doubt that muriatic acid would do a great job of etching steel or galvanized steel. Ive used it to remove rust and etch the inside of motorcycle petrol tanks and had decent results. However, I suspect it is very much a case of using a sledgehammer to crack a nut and I expect it would come with the combined risk of continuing to eat through any metal where is was allowed to rest un-neutralized. Landowner may or may not have had that problem long term but I think im going to rule it out on the basis that it is just unnecessary. Thanks for the tip though.

So the plan is:

File the excess galv out of any apertures.
Drill any holes that need drilling. (the two brackets the bolt to the footwells immediately spring to mind.
Seal those new drill holes with cold galv aerosol spray.
clean the surfaces thoroughly and allow to dry.
T wash.

Then what? If T wash has etched the surface should I go straight to a high build primer on the bulk head? or does it still need an etch primer on top of the T Wash?

Ive heard good things about Corroless so im leaning in that direction for the chassis.

meego · Tuesday at 18:38

jimllshiftit said:
Saying this from only a basic understanding of metallurgy I have no doubt that muriatic acid would do a great job of etching steel or galvanized steel. Ive used it to remove rust and etch the inside of motorcycle petrol tanks and had decent results. However, I suspect it is very much a case of using a sledgehammer to crack a nut and I expect it would come with the combined risk of continuing to eat through any metal where is was allowed to rest un-neutralized. Landowner may or may not have had that problem long term but I think im going to rule it out on the basis that it is just unnecessary. Thanks for the tip though.

So the plan is:

File the excess galv out of any apertures.
Drill any holes that need drilling. (the two brackets the bolt to the footwells immediately spring to mind.
Seal those new drill holes with cold galv aerosol spray.
clean the surfaces thoroughly and allow to dry.
T wash.

Then what? If T wash has etched the surface should I go straight to a high build primer on the bulk head? or does it still need an etch primer on top of the T Wash?

Ive heard good things about Corroless so im leaning in that direction for the chassis.

You don’t need etch primer if you have used T Wash.

jimllshiftit · Tuesday at 19:36

Fabulous, thank you.

I'll stick with the T wash process as you suggest and looking forward to reading Dags links before I start.

Looking forward to getting going on it while the weather is being kind.

dag019 · Tuesday at 21:00

I did not think t-wash was a true etch though hence I still used an etch primer on things that were getting a body coloured top coat. Everythign else is zinc 182 for as much protection as posisble.

dag019 · Tuesday at 21:04

jimllshiftit said:
Fabulous, thank you.

I'll stick with the T wash process as you suggest and looking forward to reading Dags links before I start.

Looking forward to getting going on it while the weather is being kind.

You may want to skim through some of them, two of them are rather long documenting the whole build process most of which is not relevant to your original painting question!

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