Epoxy Primer

[Dcal]

There has been a long term debate going on over many threads as to which is best, epoxy or epoxy mastic.

I don’t think there is a one size fits all solution but I do think the biggest difference is DFT (dry film thickness) and the more paint you put on the better the protection you will get, but too much paint can cause craching and is just a waste.
If you are brushing, it's very easy to get a low spot at the bottom of the brush marks, with spraying it easy to miss a bit, or not get full coverage in a blind corner.

In industry the spec usually calls for a check on DFTs (hundreds of readings) and a spark test where the painted item is earthed and a soft wire brush at a high voltage is brushed over the coating.
If there is a pin hole or other defect the equipment will register a short to earth and identify a defect which can be dealt with.
This isn’t really practical in the DIY world so a better option is to check the paint every now and again and fix any issues as they appear.
It's normally just a spot here and there, unless there is a bigger issue which need sorting anyway.

 

[Dcal]

I sprayed a bit of Jotun 90 today on a bonnet I repaired with very similar results to @Smouser.
Some of the underside had already been coated (before christmas) with 90 to fill the lumps and bumps in my welding so sanded that first.

It's the back, so I wasn't too fussy but it sanded ok.

Then worked on the front

Again this was sanded months ago, so cleaned with panel wipe and sanded with 80 abranet to get the remaining single pack (I think) spray filler off, then cleaned again.

As you can see there are lots of stone chips, rust spots and nicks where I wet too deep scraping the lacquer off, so lots of defects to sort.
I mixed 1/2 litre of paint - 350 of base, 100 of winter hardiner and 75 of thinner 17

Gave the back a couple of coats.

Then the same for the front.

I'll let it cure for a week before blocking it back and see how it looks.

 

[Furiokid]

Just wanted to say thanks to everyone for your advice leading upto today. Managed to get the shell sprayed with Letcher Epoxy Primer. Still a few more areas to clean up, and areas to repair then top up the Epoxy

 

[Smouser]

Looks good!

I hope it performs better than optima21's coating.

I am a Jotamastic man, BUT, I have not tried Letcher so my opinion is biased.

 

[Furiokid]

Looks good!

I hope it performs better than optima21's coating.

I am a Jotamastic man, BUT, I have not tried Letcher so my opinion is biased.

This is my first time using any kind of 2 pack paint, and I was going to get the Jotamastic but went with Ajlelectronics recommendation to use Letcher and have to say it went on great, only got one run that I could see due to an awkward place. Appeared to dry quick as well, but will leave it now till next weekend before doing anymore

 

[Smouser]

As I said, I am biased .

Letcher might be just as good or better. Hope it works well for you.

 

[ajlelectronics]

As I said, I am biased .

Letcher might be just as good or better. Hope it works well for you.

Just different. Lechler 29107 is designed as an automotive product, so it sprays beautifully. Jotun products are designed for non automotive products where they do a fine job. I would use Jotun products on undersides but never where the finest finish is required, such as bodywork.

 

[Dcal]

Just wanted to say thanks to everyone for your advice leading upto today. Managed to get the shell sprayed with Letcher Epoxy Primer. Still a few more areas to clean up, and areas to repair then top up the Epoxy

View attachment 282612View attachment 282613View attachment 282614View attachment 282617View attachment 282618

Looking good
A coat of paint is a great milestone, but it also shows up what work still needs to be done.

I can't agree with @ajlelectronics
If it's being sanded, the slightly rougher finish from the Jotun doesn't matter and in fact probably reduces the amount of filler you will end up needing.
If it's a new panel and you are just building up the coats, then Lechler (or any other standard epoxy primer) every time.

 

[ajlelectronics]

Looking good
A coat of paint is a great milestone, but it also shows up what work still needs to be done.

I can't agree with @ajlelectronics
If it's being sanded, the slightly rougher finish from the Jotun doesn't matter and in fact probably reduces the amount of filler you will end up needing.
If it's a new panel and you are just building up the coats, then Lechler (or any other standard epoxy primer) every time.

On your own vehicle maybe, but not on a customer's car. Jotun don't even supply application directions for conventional spray application.

 

[Dcal]

And you a not following Reliant's repair procedures, which you would expect from a specialist, so we are both out on a limb.

I'm a diyer advising (when I can) other diyers who, like me, don't have access to professional facilities, equipment or materials, so I would hope they are not looking for advice on doing customers cars.

 

[rcx132]

Good work! It should all be down hill from now, what do you have left to do?

Re the Jotun Lechler argument, I used Jotun on my first project for the undercarriage as it seems heavier duty but got fed up having so many types of paint and just use Lechler for everything now. Jotun is also very thick and messy. My bet is that the basic epoxy formula is the same for all paints and the difference is just the additives.

 

[Furiokid]

Good work! It should all be down hill from now, what do you have left to do?

Re the Jotun Lechler argument, I used Jotun on my first project for the undercarriage as it seems heavier duty but got fed up having so many types of paint and just use Lechler for everything now. Jotun is also very thick and messy. My bet is that the basic epoxy formula is the same for all paints and the difference is just the additives.

Well I had resprayed it once before in cellulose a few years ago and I was advised that if the paint was ok then no need to take back to bare metal, but I decided to redo a few bits on the shell which involved going back to bare metal and found rust/corrosion which has made me take it all back to bare metal....which has now shown me pin holes and pitting in different places so I now need to try and repair them before I can commence any further

 

[rcx132]

I was advised that if the paint was ok then no need to take back to bare metal,

Both restorations I've done the paint looked solid but when I removed it there was lots of rust underneath.

which has now shown me pin holes and pitting in different places so I now need to try and repair them

I'm fixing pin holes with lead on my project

 

[Burdekin]

Both restorations I've done the paint looked solid but when I removed it there was lots of rust underneath.



I'm fixing pin holes with lead on my project

I have some pitting and small holes in the apertures of my project, I thought about lead, welding and cutting out and not decided yet which would be best. I have never done lead loading before so would need to learn. What’s your take on doing them in lead rather than welding?

 

[Dcal]

I have some pitting and small holes in the apertures of my project, I thought about lead, welding and cutting out and not decided yet which would be best. I have never done lead loading before so would need to learn. What’s your take on doing them in lead rather than welding?

Using lead for this application is a bodge.
If it's perforated, cut it out and weld in new metal.

If you are doing a period correct restoration then lead is the only option because it was the only "filler" available back in the day.
It's not used much nowadays because it's slow, expensive and lead can cause well known health problems.
You can get epoxy or fiberglass fillers that will add more strength than the lead but that's also a bodge.

If the pitting isn't structural, grit blasting and an epoxy mastic, or better still a zinc rich epoxy, or even better still, hot spray zinc will hold it for many many years.
If it is structural, you already know the answer and you have the kit and the skills to sort it properly.

 

[Furiokid]

None of the pitting is structural on mine, some of it that looks bad (also has pin holes) I’m going to cut out and replace so I can try and access the panel behind to clean as well, but I’ve also got some surface pitting in a couple of places along the roof gutter. Not sure what I’m going to do with that yet as don’t want to be cutting it out ideally

 

[rcx132]

What’s your take on doing them in lead rather than welding?

Well cutting out metal and welding new metal is never the same, I just did one of my arches and found that as soon as I cut the bad metal out the panel sprung into a new shape. Lead is semi structural so I think if there's pitting or small amounts of rust then lead has its use.

 

[MG David]

epoxy primers do vary in protection. in June 21017 I reskinned the bonnet on my car as the orginal framework was a bit rotten and a new bonnet would look out of place on the car, so I had a new bonnet, removed the skin, took the framework back to bare metal and painted it in lechler 29107 epoxy primer on both sides

and I also brushed some gravitex on it, and now rust is showing though in places especially on the front edge of the bonnet. but this car is outside in all weathers so is a proper long term and driven once a week.

The Jotun 87 that I'm using under the car with any thing on top of it is fairing up much better.

for long term storage away from the elements I think it'll be fine long term though.

Sorry your finish hasn't lasted very long. We put so much work into these projects it can be very demoralising when this happens.

What I have found on a panel like that is you have to be careful around the holes. Paint seems not to like sharp edges and where you have a punched/pressed hole you normally find a sharp edge on one side. I now put a lot of time into rounding off those sharp edges. Initially I draw file them and then I use 120 grit paper on them. This seems to reduce the weak link effect.

 

[Burdekin]

None of the pitting is structural on mine, some of it that looks bad (also has pin holes) I’m going to cut out and replace so I can try and access the panel behind to clean as well, but I’ve also got some surface pitting in a couple of places along the roof gutter. Not sure what I’m going to do with that yet as don’t want to be cutting it out ideally

Yeah a small hole isn't a structural issue, it getting bigger or leaking is the real issue.

 

[Furiokid]

Yeah a small hole isn't a structural issue, it getting bigger or leaking is the real issue.

The ones on the roof gutter areas haven’t got any holes, it’s just pitting that I don’t want to get any worse and I can’t access the panel from behind