After media blast "rust" treatment ??

[JoeyD1968runner]

After media blast do I need to "treat" the old rusted areas with rust inhibitors prior to epoxy primer(DP90)? Or does the epoxy primer complete that task by sealing all air out ??

Thanks,Joey

 

[Mike67]

I've always been told that you want to use something like a prep and etch...

 

[Pistol Pete]

Ok, here goes...this is what I do and yes, you will get twelve different answers from eleven different people.

Wash the car with (blue) Dawn soap and yes, water, using a red scotchbrite pad. This will remove contaminates and knock down a little of the tooth left behind from the media blasting, but not so much as to affect adhesion.

Blow off with compressed air

Wipe down with SPI waterborne wax & grease remover http://media.wix.com/ugd/8ced3e_5cc7a1b533ea40588400c9791fa05960.pdf

Let flash for an hour

Spray two medium coats of SPI Epoxy http://media.wix.com/ugd/8ced3e_1e5c47ba23dd43a7a35310ee9f969705.pdf

http://www.southernpolyurethanes.com/products

PPG's DP90 used to be good stuff until they took the lead out (DP90LF) but now it just sucks.
As usual, YMMV.

 

[snakeoil24]

5wndwcpe says it well, if you have time you can let the body sit barren for 3 days max. With a dehumidifier. Do not touch the bare metal with bare hands. Finger prints will show thru any thing. If you had pit rust blasting get rid of 90 percent. You can use Straight phosphoric acid look for rust pit to turn black then remove right away. after this use dawn with distilled water then no mineral films form. Dry with leaf blower i know I'm nut's then dry with wax and grease remover.. I like to wipe with alcohol then epoxy..

 

[JimKueneman]

Agree with 5wndwcpe. If you use SPI products don't use any rust inhibitors. The epoxy has etching properties already. There is a thread there now with with adhesion problems with someone who used one of these products. Oh and use the SPI 700 then 710 grease and wax remover per the directions
Jim

 

[snakeoil24]

Agree with 5wndwcpe. If you use SPI products don't use any rust inhibitors. The epoxy has etching properties already. There is a thread there now with with adhesion problems with someone who used one of these products. Oh and use the SPI 700 then 710 grease and wax remover per the directions
Jim

I read on the Kirker instructions that Rust inhibitors leave a film behind that interferes with epoxy bond.. The modern epoxy products completely seal out moisture and oxygen..

 

[JimKueneman]

Direct quote from Barry the owner and Tech Support Desk for SPI:
"Next update.

Problem calls:


After the car has been painted and being driven the number one problem call is bubbles showing up and hands down, it is always, "I used RUST CONVERTER or METAL PREP type product in this spot" when I say these names there are many other names and products similar and I'm grouping them altogether. There is no other problem call that even comes close to the number of calls on the mention subjects.
Well over a 100 calls a year.
The calls all seem to take place in a month to 1 year after car has been finished and a number of them the first week on the road.

The third ranked call and way down the list of maybe only 20-30 calls a year is spot bubbling because of lacquer thinner being used to clean the metal."

 

[JimKueneman]

And 5wndwcpe is on the SPI boards as well so his advice has passed the "Barry" test with the SPI products.

 

[JimKueneman]

Last post, promise.... Worth 23 minutes. Barry is ok with Ospho IF you follow his cleaning procedure...but doesn't really see the need due to what was said above. It is completely sealed by the epoxy and it buys you little to nothing.

 

[JoeyD1968runner]

Thanks to everyone especially 5wndwcpe for the excellent instruction.
Now I just need to get it to the media blaster!!

Joey D

 

[Donny]

Blast. Never use water on the metal, like why? Blow it down with air, wax/grease remover with lint free towels, then shoot epoxy, period. If your blaster is any good, and if stubborn rust remains, he will use Ospho, then 24 hrs later blast the Ospho off, yup, easy as this.