Self Etching Primers

[Chuck]

Over the years I've used various brands of self etching primers with mixed results.

 

I think the worse I ever tried was the Rustoleum and Duplicolor brands. Both were dark green, shot out the can like a firehose and took forever to dry...ugh!

 

So I started using the Harbor Freight brand. Cheap at $6 per spray can, nice easy to use adjustable spray nozzle and sprayed a nice fine pattern. Downside is it sprayed so fine that even full wet heavy coats were thin. Probably why price is so low it's mainly solvents with a little pigment thrown in.

 

Stuff did dry fairly fast but I wasn't ever really satisfied with it.

 

Here's a pic of the grey self etching primer can...

 

 

It was okay but then this happened a few weeks back when priming a MTH PA1 fuel tank that was made out of clear plastic...

 

 

 

It didn't attack the plastic...more like the paint started sliding off. Self etching my ass.

 

So I searched around and found the old Zinc Chromate primer that I though was banned years ago. I used to use the DuPont stuff on aircraft frames, aluminum components etc.

 

I recently bought a can of this Marpro etch primer. Came from a marina down in Florida. Available in yellow or green. The msds shows it has Lead Chromate pigment in it along with Zinc Chromate so figured I'd give it a try. I also have some brass etched grills to prime.

 

This stuff ain't cheap at $15 per can delivered.

 

 

Here's same tank primed with Marpro...I'm sold as this will be primer I use from now on! 

 

[PAZGRR7315]

Chuck, what did you use to prep for the primer application, strip paint etc.

Bob (PAZ)

[Chuck]

Bob, For stripping I use a Harbor Freight blast cabinet with Armex as the blasting media as that won't remove the fine details. Armex is nothing more than large grained baking soda and Armex is part of the Arm & Hammer brand.

 

Those parts shown were undecorated raw plastic and all I did was give them a light "blast" to roughen them up...give the primer something to "bite" into.

 

I've done lots of blasting and can tell you that MTH uses some very tough primer as first coat. I'll bet it's a sort of etching or maybe even an epoxy primer. USA and Aristo plastic shells have no primer on them. USA aluminum passenger cars do have a tough primer as first coat.

 

 

 

[PAZGRR7315]

Thanks Chuck, will be visiting Harbor in town!

With your info, now I can prep & paint my USAT 44T's into the USAF Shaw AFB South Carolina paint scheme.

I appreciate your reply.

[Chuck]

That's great! I have this cabinet...

 

 https://harborfreight.com/40-lb-capacity-floor-abrasive-blast-cabinet-68893.html

 

And use this blasting media...

 

https://harborfreight.com/50-lbs-extra-large-grade-armex-soda-blast-media-65931.html

 

I installed different Led lighting and am using a small shop vac and a cyclone for the air evac system. Also have air regulator/ water separator on inlet air.

Compressor is a 5hp single stage and it isn't quite big enough to run the thing...never should have sold off my 7.5hp 2-stage compressor.

 

I'm thinking of putting a air operated vibrator onto the cabinet hopper as that baking soda doesn't like to "flow".

I also did the media pickup tube modification and with all that the soda blasting is still a pain in the ass...but the end results are well worth it. Over the years I've used brake fluid, purple power, pine-sol, 91% isopropyl alcohol, paint strippers etc. and I can say that the blast cabinet is the best. Environmentally friendly as not much mess compared to chemicals.      

[PAZGRR7315]

Yesterday received my Yellow Primer, cabinet delay - furnace expansion tank failure !   Bummer....