Chassis and body paint - rusty

[Jacktegla]

Iam putting a new floor in my car and wondering what to paint it with, am I est with something like rustoleum combi colour for metal or use epoxy primer and just standard paint on top. ?


Also I have light surface rust on my chassis and im going to try and clean it up but know I can't get every where, what should I be painting it with any suggestions for something that will kill the rust or convert it, is there such thing as a rust conversion primer ? Or have you got any other recommendations for painting chassis.

Thanks

 

[steveo3002]

id go with epoxy

not convinced about those rust converters myself...clean it up best you can then epoxy

 

[Dcal]

I agree with @steveo3002 epoxy every time, but sand the metal with 80 grit in a da (if you have one ) or by hand as a final prep before the epoxy. It will really improve adhesion.

Then you can put pretty much any top coat to finish it off.

 

[steveo3002]

yep needs to be rough...not polished with a wire wheel

epoxy can be left as is too ...if need be

 

[Jacktegla]

id go with epoxy

not convinced about those rust converters myself...clean it up best you can then epoxy

Ok thansk. Only problem is I cant get every where to sand it will the epoxy still adhere ok to places where its not sanded

 

[Barking Mat]

Ok thansk. Only problem is I cant get every where to sand it will the epoxy still adhere ok to places where its not sanded

No, it'll fall off with the rust, a dremel ?

 

[Dcal]

If you can’t get at it to sand it, can you paint it?
For inaccessible bits I go for a wax.

 

[steveo3002]

Ok thansk. Only problem is I cant get every where to sand it will the epoxy still adhere ok to places where its not sanded

it will stick as well as anything else ..sticks like **** to a blanket

but as with anything its only as good as the prep , if you cake it on over loose flaking rot then dont expect too much , clean it up the very best you can then it will last well , better than any other rust paint will

 

[Barking Mat]

If you can't get to the rust, get rust remover on it if you can, it does stabilise the rust and to some extent prevent degrading.

 

[bricol]

it will stick as well as anything else ..sticks like **** to a blanket

but as with anything its only as good as the prep , if you cake it on over loose flaking rot then dont expect too much , clean it up the very best you can then it will last well , better than any other rust paint will

My experience of if being ten years under a car is that it is worse then conventional paint if you cannot prep the surface to the required standard. If you can prep it properly, it is vastly superior to conventional paint.

I won't use it now on anything I can't prep right - it stays in place, held by the bits that do stick, but seems to separate from the surface and allow moisture in.

 

[Jacktegla]

My experience of if being ten years under a car is that it is worse then conventional paint if you cannot prep the surface to the required standard. If you can prep it properly, it is vastly superior to conventional paint.

I won't use it now on anything I can't prep right - it stays in place, held by the bits that do stick, but seems to separate from the surface and allow moisture in.

Ok thanks, what surface contdion does it need, its chassis so my plan is to get all the flakey crap off then try to give it a key with an orbital sander 40 grit and hand sand paper, will this be sufficient. The metal its going is is slightly pitted

 

[Barking Mat]

I'd wipe it down with acetone too, to remove grease / oil, if you're going to town.

That helps.

 

[Dcal]

Yes, that prep should be fine, but clean with panel wipe before applying the primer.

For that job I'd use jotamastic 90A because it has a bit of aluminium in it for some galvanic protection and it is surface tolerant, which means it will work with less than perfect prep, however it will work even better with better prep.

 

[Jacktegla]

Yes, that prep should be fine, but clean with panel wipe before applying the primer.

For that job I'd use jotamastic 90A because it has a bit of aluminium in it for some galvanic protection and it is surface tolerant, which means it will work with less than perfect prep, however it will work even better with better prep.

I've had a little go is that surface finish OK on the left

 

[rcx132]

If it was me, I would either go back to bare metal, which probably means removing the chassis and blasting it and if that wasn't possible I'd use some semi liquid protection which soaks thru the rust to protect the metal under it.

Lots of people swear by POR, but go on YouTube to see the fails, Epoxy and Por are super hard but if they don't go onto bare metal then the rust just creeps under the paint.

 

[rcx132]

Also Epoxy must be top coated because the UV gets it even if it's under the car and it gradually degrades. Doesn't matter what you top coat it in as all top coats should give UV protection.

 

[Jacktegla]

If it was me, I would either go back to bare metal, which probably means removing the chassis and blasting it and if that wasn't possible I'd use some semi liquid protection which soaks thru the rust to protect the metal under it.

Lots of people sweat by POR, but go on YouTube to see the fails, Epoxy and Por are super hard but if they don't go onto bare metal then the rust just creeps under the paint.

Would sanding the chassis, then using some rust converter then epoxy primer work.

 

[rcx132]

Would sanding the chassis, then using some rust converter then epoxy primer work.

Epoxy sticks to metal. Apparently it forms a bond into the metal. It won't attach to rust so water can creep under it. Some rust is ok so long as there's good metal around it to form a seal. So I'd say it depends on how much clean metal you can expose and if you have access to sand it all.

Wire brushes remove loose rust only. You're then left with something that looks like clean metal but it's just polished rust. You can apply rust converter to check, rust will go blue, clean metal won't so you can see how well the brush has done.

Rust converters are better than nothing but are not a real solution.

In summary it all depends on how much you can clean up the chassis to decide between epoxy or some sort of liquid proofer.

 

[rcx132]

I've had a little go is that surface finish OK on the left View attachment 296415

That is polished rust. Apply rust proofer if you don't believe me, and watch it turn blue. Sanding through rust is hard work.

 

[Dcal]

Would sanding the chassis, then using some rust converter then epoxy primer work.

What kit have you available?
Blasting is by far the best option, but is no small undertaking.
I did it on my Alfa 75 thread, if you want to see how it could be done with limited kit.
Next best option is a Bristle Blaster but they are even more expensive than a cheap grit blaster set up.
Needle guns are the next best tool.

I assume you used a rotary wire brush to clean the rust off but as said that is polishing the surface but it will take some of it off so well worth doing.
Take as much of the rust off with wire brushes, needle gun, grinder with flap discs etc. then sand with coarse paper to provide a key.
I'm not convinced of the miracle cures under epoxy as I've never seen one recommended by a paint manufacturer.