What would you recommend for a scratch with some surface rust?

[Suberman]

Hi fellas. What would you recommend for a 1 cm long (maybe 2mm wide) scratch with some surface rust?

I know this seems very minor and to some people, is not even a problem to begin with, but i'm quite the OCD-er and the rest of the car is really mint so i would like to deal with that as best as i can.

After some reading, the following seem to be the way:

sand or rust coverter/killer
prime with epoxy primer
paint

what do you think the best approach to dealing with it?

I'm thinking - sand off rust (it looks like it's just the surface), prime and paint?

Or would a rust converter/killer be more suitable in my case? The scratch is quite small and it's at an area that's hard to work on.

Heres the issue. There aren't many DIY products available in my country, so far i've sourced the following:

Dinitrol RC900
Dinitrol Zinc Spray (Very old can, i believe it's well over its shelf life!)
Sikkens 1K spot primer http://www.sikkenscr.com/sikkenscr/u...eraerosol.aspx
Some Spies Hecker 2K epoxy primer that my regular bodyshop spared me (needs to be mixed 1:1) Don't know which one exactly, but i'll check back with him. I'll need to apply this with a small brush.

It is on the inside of the chassis sill, so it doesn't have to be a 'perfect' repair, but i'd like do it as neatly as possible.

Thanks for any advice.

 

[steveo3002]

rust killers dont work ..and no need for something like that

id clean it up with a dremel until its clean shiney metal then prime and paint , no need to get too involved thats all you need

 

[Suberman]

Thanks for replying Steve. Good to see you here as well. DW member here as well.

What type of primer would you recommend? Like i said, i don't have access to many DIY type spray on primers, so it's either asking my bodyshop for some or the Sikkens 1k spot primer that i bought.

 

[langy]

I would clean it back to bright metal and then apply a couple of coats of epoxy primer then topcoat it.

 

[Suberman]

I would clean it back to bright metal and then apply a couple of coats of epoxy primer then topcoat it.

Thanks for replying langy. My bodyshop spared me some 2k epoxy primer (the stuff that i have to mix 1 part primer to 1 part hardener) Would that do? Would i risk having the primer affect the surrounding paint? I read that self etch primers are not suitable for repairs as they have a tedancy to do that. Also, can i sand it once it dries to flatten it before topcoating?

 

[langy]

Thanks for replying langy. My bodyshop spared me some 2k epoxy primer (the stuff that i have to mix 1 part primer to 1 part hardener) Would that do? Would i risk having the primer affect the surrounding paint? I read that self etch primers are not suitable for repairs as they have a tedancy to do that. Also, can i sand it once it dries to flatten it before topcoating?

Yes you can let it dry and sand for a key or let it dry for 60 minutes and then just put your topcoat on.

 

[steveo3002]

Thanks for replying langy. My bodyshop spared me some 2k epoxy primer (the stuff that i have to mix 1 part primer to 1 part hardener) Would that do? Would i risk having the primer affect the surrounding paint? I read that self etch primers are not suitable for repairs as they have a tedancy to do that. Also, can i sand it once it dries to flatten it before topcoating?

sounds perfect ...yes you could sand it if you wish once its dry

 

[Suberman]

Dry sanding i'm presuming?

What would you recommend i start of with? I'm thinking some 500 grit for rust removal, then 1000 grit to smooth it out. Will that be too smooth for paint to stick?

I'll be applying both primer and paint by a small brush.

 

[langy]

Dry sanding i'm presuming?

What would you recommend i start of with? I'm thinking some 500 grit for rust removal, then 1000 grit to smooth it out. Will that be too smooth for paint to stick?

I'll be applying both primer and paint by a small brush.

Yes dry sand metal with 180-240, flat primer with 600 if you want to, to be honest if its on the underside of the car i would clean the metal with 180 and then apply the epoxy and topcoat wet on wet as i described above.

 

[Suberman]

Just tested out the 2k epoxy primer on some metal poles. It seems like it's going to take a rather long time to dry out completely. Been over 5 hours, and it still gets marked by my finger prints.

Seems like i might have to apply the topcoat over the "still drying" epoxy primer. By doing so, would the paint affect the drying in any way?

 

[steveo3002]

why cant you wait 24 hrs

 

[Suberman]

Because i'm not sure if i'm doing it right and i'm the impatient type. OK Steve, i'll leave it for a fair bit longer before attempting to meddle with it.

 

[langy]

Just tested out the 2k epoxy primer on some metal poles. It seems like it's going to take a rather long time to dry out completely. Been over 5 hours, and it still gets marked by my finger prints.

Seems like i might have to apply the topcoat over the "still drying" epoxy primer. By doing so, would the paint affect the drying in any way?

Are you applying it in the cold ???

 

[Suberman]

No I'm not. Applied it in the afternoon, about 30 deg or so, it's in the middle of the night now, 24 deg. I'm from Singapore fellas. So it's always warm here. If this primer requires oven drying, it will still eventually dry?

 

[langy]

It should be hard enough to sand next day, I usually leave my epoxy 16-18 hours before sanding, What make was it ??? Was the mixing ratio correct ??? All the makes of epoxy i have used have been 2-1 or 3-1

 

[Suberman]

It should be hard enough to sand next day, I usually leave my epoxy 16-18 hours before sanding, What make was it ??? Was the mixing ratio correct ??? All the makes of epoxy i have used have been 2-1 or 3-1

It's a Spies Hecker one, given by my bodyshop. He said it's 1-1. Hmmm.... I'll get the confirmed part number tomorrow. Then I can checkout the TDS to see the mixing ratio.

 

[steveo3002]

im sure it will be fine in the morning

 

[Suberman]

Yes you were right Langy, the mixing ratio was wrong (as instructed by the chap!) It is 2:1.

It was Spies Hecker 4090 which is a epoxy based primer surfacer formulated for commercial vehicles. Just checked out the TDS, correct application seems a bit difficult for a DIY job.

Will some 1k wash (etch) primer work in my case?

He gave me some. Just read through the TDS, it seems suitable for spot repairs but i've read that etch primers are no go for sport repairs as they can/will lift surrounding paint?

 

[langy]

I think you maybe overthinking this small job mate, just leave the Epoxy to go hard, key i and apply topcoat.

 

[pedrobedro]

I'd have slapped a couple of brushfuls of Zinc 182 or used the Dinitrol spray straight on it and then painted it when it dried, half an hour tops in the temperatures you are talking there. Is it some kind of exotic supercar or expensive vintage motor ?