Chassis & wishbone coating final solution

Chassis & wishbone coating final solution

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Discussion

caduceus

Original Poster:

6,069 posts

265 months

Monday 23rd February 2015
quotequote all
Chassis and other coated bits are nearly ready to go to the blasters, so I'm thinking still about what is thee best route to go in terms of coating and longevity.

Have the TVR fraternity come to a conclusion as to what the best treatment is for our chassis and wishbones, etc?

Cad

Cokes

475 posts

113 months

Monday 23rd February 2015
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What he ^^^ said, I'm next so I wait with great anticipation on what I hope is the best solution.

ChimpOnGas

9,637 posts

178 months

Monday 23rd February 2015
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1. Media blast

2. Repair with new steel

3. Media blast again to key new steel

4. Immediately hot zinc spray

5. Pacify zinc with mordant solution (T-Wash or similar)

6. Acid etch prime

7. Two coats red oxide colour epoxy mastic

8. Final top coat in silver/grey epoxy mastic

9. If chips appear will show as red spots against silver/grey top coat - touch up with brush using silver/grey epoxy mastic

10. Drive for 40 years before any serious remedial work needed

As always with any top coat (no matter how good it is) correct preparation is absolutely key to achieving a decent finish & longevity!!!!

Forget powder coat, even the best powder coat job is utter rubbish when compared with just one coat of epoxy mastic over a decent acid etch primer.

ClassiChimi

12,424 posts

148 months

Monday 23rd February 2015
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That sounds about perfect to me ,, 40 years of rust free Tvr,,
It'll stand longer than an oil rig.
Dave you've got me thinking,,, it's time I secured my chassis future properly,
What peace of mind that would give...
Excellent answer sir.

TJC46

2,147 posts

205 months

Monday 23rd February 2015
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Lots of different opinions on this one.

My own choice [which i did to my chassis] was full chassis degrease and inspect, new seamless tubing for the outriggers, bead blast and 2 pack epoxy primer on straight after, and i mean straight after blasting.

4 more further coats of 2 pack epoxy, alternating between grey and red oxide colours, to ensure full coverage.

Final coat of 2 pack epoxy gloss in bright red, and finally top coat of clear lacquer for stone chip protection.

Wipe down and inspect every winter, and it looks just like the day i did it.

Whatever you both choose, i would, in my opinion, avoid powder coat. Yes its much better now than when TVR made a joke attempt at it, and its quick and convenient, but you hope to never have to do this job again, so do it right, however long or

laborious it may be.


J400GED

1,202 posts

236 months

Monday 23rd February 2015
quotequote all
Cokes said:
What he ^^^ said, I'm next so I wait with great anticipation on what I hope is the best solution.
Race you.
Mind you you've got a mate helping you and I've got a teenage daughter helping me!

caduceus

Original Poster:

6,069 posts

265 months

Monday 23rd February 2015
quotequote all
J400GED said:
Cokes said:
What he ^^^ said, I'm next so I wait with great anticipation on what I hope is the best solution.
Race you.
Mind you you've got a mate helping you and I've got a teenage daughter helping me!
I've had neither so far frownhehe Dropped the diff on my chest today. A LOT heavier than I was expecting! Seems heavier than the gearbox FFS.

Back on topic, I do like the sound of the multiple coats. Definitely don't want to touch powder coating.

One question. Apart from the media blasting and welding, how many of the steps can be carried out by oneself at home?

Thanks for the replies so far. I was expecting a long and in depth discussion about which method/s is/are best, and why. But it seems, for longevity, we have already found a tried and tested process fro the time being.
I was going to do research on marine applications and some motorsport firms (Paris Dakar) on their processes. May still do, but am liking the sound of the epoxy mastic. I assume its no where near as brittle as powder coat?

Cokes

475 posts

113 months

Tuesday 24th February 2015
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Thanks COG and TJC for your replies. It's exactly what I wanted to hear. In 40 years I'll be the one rotting and my chassis will live on.

J400GED said:
Race you.
Mind you you've got a mate helping you and I've got a teenage daughter helping me!
Marcus will help out where and when he can but its only going to be a couple of hours a week with any of the heavy stuff.


caduceus said:
I've had neither so far frownhehe Dropped the diff on my chest today. A LOT heavier than I was expecting! Seems heavier than the gearbox FFS.
I found the diff surprisingly heavier than it looked when I finaly got it free from the chassis above my head curse

Edited by Cokes on Tuesday 24th February 05:36

ChimpOnGas

9,637 posts

178 months

Tuesday 24th February 2015
quotequote all
TJC46 said:
Lots of different opinions on this one.

My own choice [which i did to my chassis] was full chassis degrease and inspect, new seamless tubing for the outriggers, bead blast and 2 pack epoxy primer on straight after, and i mean straight after blasting.

4 more further coats of 2 pack epoxy, alternating between grey and red oxide colours, to ensure full coverage.

Final coat of 2 pack epoxy gloss in bright red, and finally top coat of clear lacquer for stone chip protection.

Wipe down and inspect every winter, and it looks just like the day i did it.

Whatever you both choose, i would, in my opinion, avoid powder coat. Yes its much better now than when TVR made a joke attempt at it, and its quick and convenient, but you hope to never have to do this job again, so do it right, however long or

laborious it may be.
^^^^^^ This ^^^^^

Virtually exactly what I'm suggesting in my earlier post.

I don't care what anyone says, even the best powder coat job is utter rubbish when compared with a two part epoxy based wet paint system.

People should know powder coat does not chemically bond with the substrate, it is effectively a wrapping, once breached water will pass between it and the substrate, just one small stone chip is enough to start the process and the resulting corrosion is both inevitable and impossible to stop without media blasting the affected area and applying a new top coat.

Localised repair of breached powder coat is rarely successful in the long term because no matter how hard you try to remove the powder coat from the affected area you almost inevitably never take it back far enough, also the edges of the powder coat in your prepped are creates a zone of extreme vulnerability.

If you do have to touch up powdercoat you'll be using a brushable wet paint system anyway, in which case PoR15 works well but no matter how good the paint is, touching up breached powder coat is merely delaying the inevitable.

Acid etch primers themselves do not offer protection, however what they do is chemically bite into the substrate forming the perfect key, in turn the two part epoxy based wet paint system will bond to the etch primer.

Nothing (& I mean nothing) offers better resistance to corrosion for mild/high carbon steel than galvanization, look at farm gates, motorway Armco & street signs, all galvanized with no top coat and lasting for years.

When it comes to top coats, nothing (& again I mean nothing) is as tough and durable as a decent two part epoxy based wet paint system, and epoxy mastic paints offer additional protection against abrasion damage (stone chips in our case) due to their incredibly flexible high solids.

Combine galvanization (even hot zinc spray) with a decent two part epoxy based wet paint system (preferably epoxy mastic) and as long as the zinc is pacified with a mordant solution and an acid etch primer is used before applying the epoxy mastic the steel beneath it will last indefinitely.

Powder coat is a decorative finish, you never see it used in tough marine environments because it wouldn't last 10 minutes.

Epoxy is a thermosetting epoxide polymer, thermosetting means that epoxy is an adhesive that cures and cannot be uncured.

An epoxide is simply a chemical that is more reactive to other chemicals; however, a polyepoxide, such as epoxy, is comprised of unreacted epoxide. This means that pure epoxy is very susceptible to reaction with other chemicals.

The other chemical in the case of epoxy is a hardening or curing agent, which reacts with the polyepoxide to cure into a very strong adhesive.

The chemical reaction creates heat, anyone who's mixed up some two part body filler will be familiar with this and the bullet proof strength of the end product. Mix up some Areldite on a sheet of glass, once set remove it and have a play with what you've got, a virtually indestructible polymer.

Two part wet paint systems work in exactly the same way, immediately prior to application the hardener is added, the chemical reaction taking place as the paint system cures on the substrate.

These paints are often referred to as 2k (Two Pack) ie they are a two part chemically reacting system just like body filler or an epoxy based adhesive like the brand name Araldite we are all familiar with.

If you really want your chassis to last you've got to forget powder coat and move onto what the marine industry has been using for decades.

An Epoxy Mastic Wet Paint System!

To test all this simply paint a sheet of glass with epoxy mastic, once cured peel off the coating and see what you've got.

You'll have an incredibly tough sheet of flexible polymer that will exist long after the next Apocalypse wink

Intershield 803 or better still the even more durable Intershield 803Plus from International paints are the best marine environment two part epoxy mastic paint systems out there bar none.

International paints make the very best industrial marine coatings, period!

http://www.international-marine.com/cargoholds/car...

zed4

7,248 posts

221 months

Tuesday 24th February 2015
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Quick question for you...

I’m in the process of repainting the front part of my chassis, just to tidy it up. The powder coat is mostly perfect, but in a few areas it’s flaky. In those areas I’m flaking off the old powdercoat, rubbing it back to bare metal with the dremel and then sanding it back to shiny metal, before finally coating it with Neutra-rust to be sure. Otherwise I’m just keying the powdercoat and repainting. I’m then painting it with epoxy mastic.

My question is, where I have sanded back to bare metal and then treated with neutral-rust, should I just paint over the top of this with the epoxy mastic (as advised by the supplier) or should I really be using a primer?

I am going to use a zinc etch primer (perhaps you could recommend one?) for all of the wishbones and other removable parts, as they’ve been hot zinc sprayed, but is it required for bare mild steel? I seem to remember that epoxy mastic sticks well to bare (keyed) steel.

Thanks,

Dan

caduceus

Original Poster:

6,069 posts

265 months

Tuesday 24th February 2015
quotequote all
ChimpOnGas said:
1. Media blast

2. Repair with new steel

3. Media blast again to key new steel

4. Immediately hot zinc spray

5. Pacify zinc with mordant solution (T-Wash or similar)

6. Acid etch prime

7. Two coats red oxide colour epoxy mastic

8. Final top coat in silver/grey epoxy mastic
A few questions COG.

-I assume the hot zinc spray has to be done by a company?
-When you used the T-Wash, did you apply, leave and wash off, TWICE?
-Can you recommend an acid etch primer pls? Spray or brush on?
-With regards to the epoxy red oxide (PRIMER?) and top coats; did you brush the epoxy on, or spray it on (aerosol?)?
-Did you only put on one top coat?

Many thanks
Cad

ChimpOnGas

9,637 posts

178 months

Tuesday 24th February 2015
quotequote all
zed4 said:
Quick question for you...

I’m in the process of repainting the front part of my chassis, just to tidy it up. The powder coat is mostly perfect, but in a few areas it’s flaky. In those areas I’m flaking off the old powdercoat, rubbing it back to bare metal with the dremel and then sanding it back to shiny metal, before finally coating it with Neutra-rust to be sure. Otherwise I’m just keying the powdercoat and repainting. I’m then painting it with epoxy mastic.

My question is, where I have sanded back to bare metal and then treated with neutral-rust, should I just paint over the top of this with the epoxy mastic (as advised by the supplier) or should I really be using a primer?

I am going to use a zinc etch primer (perhaps you could recommend one?) for all of the wishbones and other removable parts, as they’ve been hot zinc sprayed, but is it required for bare mild steel? I seem to remember that epoxy mastic sticks well to bare (keyed) steel.

Thanks,

Dan
Truth is you dont necessarily need to prime before using an epoxy mastic, but I like etch primers as they do key bare steel very well and are essential with pacified zinc finishes (galvanization) & aluminum.

An acid etch will work as a tie coat, both chemically biting into the steel substrate and providing an inert surface coating for the top coat to bond to, in effect you are still bonding your top coat to the substrate but the etch primer will mitigate reaction and promote adhesion.

Zinger is a zinc rich primer that's a good alternative to etch.

http://www.zinga-uk.com/

If you use an etch go with a quality one like U-Pol no 8.

http://www.u-pol.co.uk/product-cat/35/acid%238%E2%...

Remember an acid etch primer should be applied extremely lightly, you are looking to achieve good coverage but only at a few microns thick, it only works in a very light coat, over apply & it will flake.

Spray it, never use a brush, AirArsHoles as my old painter used to call aerosols are for amateurs. However in the case of acid etch primers the rules can be bent. You will often see professional paint shops using U-Pol no8 in an aerosol for localized spot repairs as the truth is a rattle can work well in these circumstances and will save a lot of gun cleaning time.

Etch prime applied by AirArsHole is only practical & cost effective for small spot repairs, if the area is any bigger than an apple you're better off getting the gun out.

Be careful though as acid etch primers are water permeable, they are not a protective top coating and should never be thought of as such.

You need to get your very fine coat of etch on the bare steel literally minutes after blasting. Keep in mind a blasted surface is not only the perfect key for primers and top coats, it is also the perfect surface for oxidization to start.

I've seen blasted steel start to go brown in hours (sometimes under an hour), ignore anyone that tells you not to worry it's just surface rust, rust is rust and you should never paint over it.

Once you've etched the steel properly you need to be keeping the work in a dry environment, areas of high humidity are a very bad thing. As such getting your epoxy mastic top coat on as soon as possible is good practice.

Zinger & U-Pol #8 are both excellent products but are the expensive brand name end of the market, I recommend finding your local professional auto re-finishing factors and discussing their trade products.

Normally they are the equal of the brand names at a vastly reduced price, however quality coating products are never cheap so if the price looks too good to be true... it probably is.

It's also worth talking to steel fabricators to see what they use, especially steel fabricators that do a lot of work for the off shore oil industry.

Listen to what these guys tell you and pay attention, keep in mind they know a lot more than you or I about corrosion protection coatings because it's what they do for a living.

Edited by ChimpOnGas on Tuesday 24th February 11:14

ChimpOnGas

9,637 posts

178 months

Tuesday 24th February 2015
quotequote all
caduceus said:
-I assume the hot zinc spray has to be done by a company?
Yes, it's a serious industrial process and must be applied by a professional in an professional environment. The process is dangerous and the equipment is expensive, the operator must use fully hooded suit that can withstand being sprayed with molten zinc for a number of seconds without burning the operator.


caduceus said:
-When you used the T-Wash, did you apply, leave and wash off, TWICE?
Apply and wash off immediately with water, it is not a coating but a pacification process that leaves the zinc inert ready for your prime or top coat. If you didn't pacify the zinc your top coat would flake and fall away in days. The other way to pacify galvanized steel is to let it weather outside for a good six months to a year, T-Wash just gets you to the same place within an hour of application. An acid etch primer is further assurance you top coat will tie to the zinc coated substrate.


caduceus said:
-Can you recommend an acid etch primer pls? Spray or brush on?
U-Pol #8 or any good quality product your local paint shop has tested and is happy with.


caduceus said:
-With regards to the epoxy red oxide (PRIMER?) and top coats; did you brush the epoxy on, or spray it on (aerosol?)?
Forget aerosols, a 2k coating is a professional product that requires professional application methods in proper paint shop environments. Sure, you can apply epoxy mastic with a brush for spot repairs and it will work well. But if you want a decent finish on a whole bare chassis, take it to a professional paint shop.


caduceus said:
-Did you only put on one top coat?
Two coats of epoxy mastic is easily sufficient if applied correctly to a properly prepared surface, as with all paint work preparation is king. Alternate the pigment colours, epoxy mastic coatings usually come in two colours, grey and something that replicates the old red oxide colour. The red oxide colour is just a pigment it is no better or worse at resisting corrosion than the grey stuff. Once upon a time genuine red oxide paint was the go-to for corrosion protection but it only achieved this because it was full of lead, genuine red oxide paint was phased out in the 1970's because it's fekin deadly. If you ever find an old tin of red oxide paint from the 1960's or before you need to immediately take it to your local recycling centre for correct disposal, dont even open the tin!

Personally I'd go with a three coat belt & braces finish over the etch prime using the latest airless gun system which is far better suited to the high solids high viscosity nature of epoxy mastic. Start with grey, over coat this with the red oxide colour and then apply your final grey coat as the top finish, alternating colours will ensure good coverage of each coat as it acts as a visual reference of where you've been and what you've missed. The final grey finish will leave the chassis looking very much like the powder coat on a 1994 - 1996 Chimaera.

If you have a later car and must have white, I'm sure you can find a white pigment epoxy mastic without too much searching.

caduceus

Original Poster:

6,069 posts

265 months

Tuesday 24th February 2015
quotequote all
Thanks for the detailed reply COG.

By the sound of things, once the chassis is stripped, it's out of my hands. Sounds like all of the processes are to be outsourced.
Do you have any ballpark figures of what the costs are likely to be all in? Going to be the best part of £1k isn't it?

TJC46

2,147 posts

205 months

Tuesday 24th February 2015
quotequote all
Here is a previous discussion on this very subject

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Contained in my post within this discussion is a link to a supplier of International paints.

Any supplier will do, I just used this from the internet as an example.

All 2 pack paint is brush-able, some say its better brushed on as you achieve a thicker coating.

All this can be done at home in your garage.

Do any welding etc. and take it to be blasted and primed straight after.

The rest can be done at home in the garage at your leisure.

You could use single pack epoxy paints if you wished although 2 pack is better.

Single pack requires no hardener mixing in, you can use it straight from the tin.

With 2 pack, the first primer coat is very important.

I used 2 pack, international 356, dark grey primer. This will paint over anything, or any other types of paint. This is the base coat in theory. The other that I used was again 2 pack International 670 light grey/red oxide. This will only go on over 356 or similar. It will not go on over other types of paint as it just bubbles and lifts it off
Final coat was 990 gloss in red again a 2 pack. This will go over both 356 base coat and 670 intermediate coat

Final thing to remember with 2 pack paint, mix it in small quantities as it will start to harden after an hour or two.

We use these paints all the time at work, so any further questions just ask.

pb450

1,301 posts

159 months

Tuesday 24th February 2015
quotequote all
Mine was 'done' last year. Shot blasted, repaired, shot blasted again and hot zinc coated. (Metalization.) Two coats of sealer, followed by two coats of 2-pack primer, then two coats of 2-pack polyurethane paint, all applied by spray.

I'm told the products used are the same as those applied to Westminster Bridge in London during a refurb a couple of years back and should be good for at least 30 years. Bearing in mind I'll be approacing 90 by then I'll probably be past caring at that point! smile

ChimpOnGas

9,637 posts

178 months

Tuesday 24th February 2015
quotequote all
caduceus said:
Thanks for the detailed reply COG.

By the sound of things, once the chassis is stripped, it's out of my hands. Sounds like all of the processes are to be outsourced.
Do you have any ballpark figures of what the costs are likely to be all in? Going to be the best part of £1k isn't it?
A professional finish requires a professional, and he needs to be working in the right environment using the right equipment to achieve the right result.

My best advice is to find someone who offers blasting & immediate priming on the same site, most blasters will offer a basic priming service. You want to avoid transporting the freshly blasted bare chassis, you must get something on it immediately.

That something could be as basic as a quick flash over of a common primer, you should also understand it's common practice to complete the blasting process twice. The first blast is used to see whats left, a second light blast is completed after the new steel has been let in.

Obviously its only after the second blast you'd be doing the sprayed or hot dip galvanizing on the fully repaired chassis.

Hot zinc spray is extremely effective but nowhere near as good as a proper hot dip process, the problem with hot dip galvanization is you risk distortion and you need to drill the chassis with drainage holes to let the hot zinc flow out when it's lifted from the tank.

The finish left by the sprayed hot zinc process is porous so it does need a top coat, whereas hot dip galvanizing delivers a proper metallurgical bond and can be just left as is. Both need pacifying with mordant solution which will turn your lovely shiny zinc coated chassis into an ugly dull black thing that looks like you've just pulled it out of the local canal. But if you don't pacify the zinc your paint will definitely not adhere correctly.

On balance the hot spayed method is simply more convenient & far more suitable for a TVR chassis than hot dipping, it still offers excellent corrosion resistance if top coated but it is more expensive at approximately £30 per Sq meter, hot dip galvanization will be about a third of that.

If you want to understand how much the whole process will cost including the epoxy mastic top coats you've got to find someone who does it and ask them.

But if hot zinc spraying is £30 per Sq meter then the 2 or 3 top coats will probably be roughly the same, so lets say a total of £60 per Sq meter for the whole process including blasting.

Before you ask I have no idea how many Sq meters a TVR chassis is, but it is an intricate structure of multiple tubes so wont be the easiest to work with requiring time to ensure a thorough and uniform coverage is achieved.

This type of work is quoted on a case by case basis after assessing the complexity of the job, for that the operator will need to physically see the chassis.

Southways Automotive have a lot of TVR chassis restoration experience and work with a blaster that also offers hot zinc spraying, they normally follow with powder coat but I know they have worked with enlightened customers that like me prefer a proper two component wet paint system.

All this means Southways are definitely the people to go to for a quote, with their blasting & zinc spray partners they can process your chassis from start to finish, including completing accurate repair work themselves.

Just ask them for epoxy mastic rather than powder coat and you'll end up with a chassis that will last virtually indefinitely, from what I've heard the quality of their work is excellent and their rates are very good value for what you get.

Just keep in mind that cheap & good value are very different things, I'm sure whatever they quite it'll be realistic & worth every penny.

http://www.southwaysautomotive.co.uk/



ChimpOnGas

9,637 posts

178 months

Tuesday 24th February 2015
quotequote all
pb450 said:
Mine was 'done' last year. Shot blasted, repaired, shot blasted again and hot zinc coated. (Metalization.) Two coats of sealer, followed by two coats of 2-pack primer, then two coats of 2-pack polyurethane paint, all applied by spray.

I'm told the products used are the same as those applied to Westminster Bridge in London during a refurb a couple of years back and should be good for at least 30 years. Bearing in mind I'll be approacing 90 by then I'll probably be past caring at that point! smile
^^^ Proper Job ^^^^ bow

Who did that for you?

It must be nice to completely banish all the powder coat to the bin where it belongs.

Like you say that's a finish that will easily last 30 years or more, clearly you subscribe to the following wink

"Do it right, do it once"

thumbup

Tyre Tread

10,525 posts

215 months

Tuesday 24th February 2015
quotequote all
Peter, would you mind giving an indication of costs please?

portzi

2,296 posts

174 months

Tuesday 24th February 2015
quotequote all
ChimpOnGas said:
pb450 said:
Mine was 'done' last year. Shot blasted, repaired, shot blasted again and hot zinc coated. (Metalization.) Two coats of sealer, followed by two coats of 2-pack primer, then two coats of 2-pack polyurethane paint, all applied by spray.

I'm told the products used are the same as those applied to Westminster Bridge in London during a refurb a couple of years back and should be good for at least 30 years. Bearing in mind I'll be approacing 90 by then I'll probably be past caring at that point! smile
^^^ Proper Job ^^^^ bow

Who did that for you?

It must be nice to completely banish all the powder coat to the bin where it belongs.

Like you say that's a finish that will easily last 30 years or more, clearly you subscribe to the following wink


Proper job



"Do it right, do it once"

thumbup
Proper job indeed. I want to still be driving my chim when l'm 70 and having to double bag my waterworks. Cost is irrelevant as you don't need to do it again;)