Is this a good idea to coat an engine bay in first before an overcoat in normal grey primer?? From what iv been told its a good base coat to use over rusty metal, obviously after the rust has been rubbed back as much as possible.

Is there any truth in this??

dan

 

apparently acid etch primer is good over slight rust and stuff it actually etches it self to the surface , this is what ill be doing to mine then noraml grey primer over the top of that, hope this helps, mark.

 

red oxide is non porus grey is, if you spray grey over bare metal it will rust, if you use red oxide it seals the metal and it wont re rust if that makes sense

 

so does acid etch primer come in grey or red and will it rust ?

 

Not sure, only seen yellow acid etch and no it wont rust but it doesn't matter as long as you cover the primer with paint the moisture wont get at it whatever you use.

 

acid etch primer can also be pink when its mixed as we use it at work to paint phone masts

 

so you cant spray bare shiney metal with ordinary grey primer?

 

doesnt look like it mate no

 

So out of the two acid etch primer is the better one, however both do a good job of sealing previoulsy slightly rusty bodywork??

which you then can coat in grey primer before a colour coat?

 

I got informed that Zinc primer can also be used.. is that right?

I thought etch primer was for other metals, such as aluminium?
My mate had to use it on a landrover before the other coats...

 

you can paint normal primer over bare metal, as long as your not leaving it over a period as it is pourus.....in other words cover it with the top coats asap....red oxide is better to paint bare metal if you dont intend top coating right away.

 

ok, will it be ok then to seal slightly rusty bodywork? i.e. stop the rust coming through again??

 

You wont stop rust with ANY paint mate. Once rust has started to eat away at metal it will carry on till it is removed. Either cut it out, or shot blast it.

 

or treat with repeated coats of jenolite and a grinder with a wire brush on if you havent access to shot blasting, zinc based primers arent great either. In this weather its also a bad idea to be spraying unless youve got somewhere heated to do it.