Epoxy Primer

[Burdekin]

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

Yeah that's the thing, a weld repair can leave a unpainted area that you can't treat easily to then prevent it from rusting from the inside or maybe causing some distortion that then needs more filler.

 

[Dcal]

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.

That’s a very good point.
It is also a well-known issue in industry and why, for the highest protection in high exposure areas, all sharp edges are rounded (2mm radius is enough) and why stripe coating (brush painting) is required before spraying.

Another point worth considering when sanding is the edges and corners are the places you are going to rub through first, which is why different colours for each coat is a very useful trick.

 

[rcx132]

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.

Good tip. With holes, once painted, I also put a dab of underseal on them as the stuff spreads out and recovers if for example the bolt going thru the hole chips the paint off.

 

[Kram]

which is why different colours for each coat is a very useful trick.

Can I add a small amount of basecoat to epoxy primer to tint it for the last coat?

 

[steveo3002]

for the home user the fact it wont suck up moisture and possibly ruin the job with microblisters is good enough to stick with epoxy through the job

 

[Dcal]

Can I add a small amount of basecoat to epoxy primer to tint it for the last coat?

I wouldn't risk base coat however SML (and probably any Jotun stockest) sell tinter for the job.

Primer Tint 90ml

www.smlprotectivecoatings.co.uk

 

[Furiokid]

Yeah that's the thing, a weld repair can leave a unpainted area that you can't treat easily to then prevent it from rusting from the inside or maybe causing some distortion that then needs more filler.

That’s one of my concerns. Is there a way of putting a coating on the back of repairs before welding them in?

 

[ajlelectronics]

That’s one of my concerns. Is there a way of putting a coating on the back of repairs before welding them in?

You can use weld through primer initially, then make good with epoxy.

 

[Burdekin]

That’s one of my concerns. Is there a way of putting a coating on the back of repairs before welding them in?

Weld through primer which is basically a single pack zinc paint. At the weld and around it will be no protection. If you can get in to spray a wax protection after welding I would also recommend spraying in a decent rust converter first. Rust converter works as a reasonable protection against rust and then a decent wax protection is about as good as you can get. It's just not always possible to get okay or any access from the back.

 

[Little Jerry]

I'm using Eastwood internal frame coating (which comes with a multi directional flexible extension wand) for the back of welds that are difficult / impossible to access. It's a light viscosity type paint as opposed to wax etc and because its very fluid it runs into every nook and cranny. Not cheap though in Australia.

 

[Burdekin]

I'm using Eastwood internal frame coating (which comes with a multi directional flexible extension wand) for the back of welds that are difficult / impossible to access. It's a light viscosity type paint as opposed to wax etc and because its very fluid it runs into every nook and cranny. Not cheap though in Australia.

Looks like a rust converter, I'd use a good wax after like Dinitrol ML as well.

A good few years back the gas terminal I work for went around and coated a lot of external corrosion areas with Navy Steel rust converter (https://www.navysteel-rust-converter.co.uk/) and these areas have held up really well so I am a convert to treating internal cavities with a rust converter before wax. The good companies that do car rust treatments also do this. It also works well as a primer as a hold coating to stop rust during projects, just topcoat with a single pack steel paint.

 

[Dcal]

Interesting.
You can get it over here as well, but I'll not be paying almost £40 for a spray can to try it out.
I'd like to see a TDS or a MSDS, but they don't seem to be available which is never a good sign.

The problem with really thin coatings is just that, they are thin and will only give a limited amount of protection.
You can get a wash primer (sometimes called blast primer, holding primer or shop primer) which is the sort or coating that would be used on blasted steel that is not going to be properly painted immediately. It's great to use because it is like spraying thinners.
It normally keeps the steel good for days or at best weeks in a less than ideal conditions.
Link below to a good, two pack one.
Only £5 odd a litre but you have to buy 20 litres so not so good if you only want to try it out. Note the description says "temporary protection".

Sherwin Williams Macropoxy G280

Macropoxy® G280 2-pack epoxy zinc phosphate primer. For application to surfaces which have been prepared by wet abrasive blasting.

www.swpaintsonline.com

I'm sure there are other things in the Eastwood stuff, but it looks like expensive snake oil to me.

@Burdekin post came as I was writing this bull and I agree with him, a non-rinse rust convertor and a good wax will probably do a far better job.

 

[Furiokid]

I had a conversation today with a guy who we use for our smart repairs (but he does bigger work as well), and he was asking about my project. He asked what colour I was going, and I said that I was going to have to use cellulose as doing it on my drive and I can’t justify the cost of an surfed mask to 2 pack....to which he replied and said that he uses 2 pack all the time and only uses a normal 3M respirator same as I’ve got, and he only uses air fed for much bigger jobs, and that for the size of my shell it’d be fine without an airfed if doing the inside one day then outside the next.

Didn’t really know what to say as he’s been doing it years and it’s not my trade

 

[vw1]

I wouldn't be happy without the correct airfed equipment.

 

[ajlelectronics]

I had a conversation today with a guy who we use for our smart repairs (but he does bigger work as well), and he was asking about my project. He asked what colour I was going, and I said that I was going to have to use cellulose as doing it on my drive and I can’t justify the cost of an surfed mask to 2 pack....to which he replied and said that he uses 2 pack all the time and only uses a normal 3M respirator same as I’ve got, and he only uses air fed for much bigger jobs, and that for the size of my shell it’d be fine without an airfed if doing the inside one day then outside the next.

Didn’t really know what to say as he’s been doing it years and it’s not my trade

Smile sweetly and say nothing. I have a mate who did the same, until he got asthsma.

 

[Kram]

The other option is brushing/rolling 2k acrylic and polishing it back. My test did not go to plan but others have had good results. I used the wrong roller with not enough thinners, I will do a brush test soon.
Isocyante does not evaporate, it is only an inhalation risk if it is atomised by a spray gun, or if it gets on your skin/eyes etc. Read the HSE documents.

Spraying on your drive, likely to be other people without any mask being put at risk. Its a bad idea.

 

[Olderisbetter]

All very interesting as i had to get all the paint off my beetle roof as it has micro blistering all over, at the moment it is just sat with a coat of rattle can upol etch primer and a few coats of stanard primer

 

[Furiokid]

Spraying on your drive, likely to be other people without any mask being put at risk. Its a bad idea.

That was another reason why I didn’t think it was a good idea, just wanted 2 pack purely for being more hard wearing that was all

 

[Keith 66]

Back in 1990 i had a 1500sq ft workshop so spraying the Morris truck in house was logical, it was done in 2 pack & we used 3m carbon filtered respirators. Today i dont have the luxury of that big workshop, far from it. I wont be spraying anything so will have to bite the bullet & get it done professionally. I wouldnt spray anything at home too much risk of getting overspray on someone elses car.
I saw similar once, I was working for a mate on a big steel motor yacht, He got a bucket of single pack epoxy primer & started rolling it onto the superstructure. He was flying along with the roller flinging speckles of grey paint everywhere. I noticed the next door boat a classy 43 ft yacht with mirror finish navy blue topsides was covered in it so gave him a can of thinners & an old shirt, "Nah i will do it later", "Do it now before it goes off" sez i. He cleaned the whole side of that boat & just 15 minutes later the owner turned up. Lucky escape!

 

[marlinspike]

I have a Gerson mask which is supposedly good for 2k up to a max numbers of hours. I don't use it with 2k but it's a very tight fit and you don't smell a thing; I can see why it would be easy to get confident about using it for long periods. I think there's a world of difference between doing a smart repair for a few minutes outside and doing a whole car though, whatever the size. Plus, as with many respiratory illnesses, the effects come years after the damage was initially done.