Topic: Sandblasting and painting before it rusts, is there a way to lengthen this?

[manjisann]

To practice before I actually work on my bike I sanblasted my friends snow blower and am going to repaint it. It has taken me over a week to sandblast everything and in that time some of the first blasted items rusted  I am wondering, is there a way to keep this from happening before you paint like spraying it down with WD40? I realize the WD40 will have to be removed, but since I wipe everything down with grease remover before painting anyhow would this still pose a problem?  I am using catalyzed paint so I don't want to have to mix up a bunch of small batches and have to clean the guns a dozen times when I can just mix up a medium sized batch and spray everything in one session. How do you do it?

Thanks,

Brandon

[kghost]

I'd be hesitant to Put WD-40 on it.....sounds like a recipe for fisheyes.........

You never get it quite clean with a wipedown.

What I often do is bring the parts inside where its airconditioned.

The A/C squeezes much of the humidity out of the air....and keeps the rust down.

Now....I generally epoxy prime before paint......

What I would recommend...and it still involves gun cleaning....is blast a days worth.

Then epoxy prime it the next day.

Once primed it won't rust...and then you can paint the whole batch at once.

[Mdub]

I have found that fogging oil (oil in a spray can) works well.

[Hush]

Nah Brandon I'm with Kghost on this, drive that sucker right into your mum's lounge and leave it by the aircon for a few days, you never know it may grow on her...or you may have to move out.

[mcuozzo]

Heh, that's nothing.  With the humidity here I swear the back side of my blasted parts rust before I finish the other side!

After I blast I use this product http://www.eastwood.com/hotcoat-powder-coating/prep-stripping/eastwood-s-metal-wash.html.  It prevents flash rusting just like it says.

I usually wash the part with denatured alcohol, MEK or acetone before coating though.  Not to really remove the metal wash but gets rid of dust or other contaminants before coating.

I bet a auto paint store might have a similar product.  I use eastwoods because I get other stuff from them, mostly powders.

Hope that helps...

[jumpjg]

I believe the main ingredient in the Eastwood product mentioned by mcuozzo is phosphoric acid. It leaves a barrier that keeps the part from rusting (will also remove flash rust), and it promotes paint adhesion. It is the same main ingredient in the POR-15 Metal Ready, the etching agent that comes in their gas tank coating kit.

I've heard that a product that uses phosphoric acid  is available in gallon jugs from farm supply stores (Tractor Supply?). Below is quote from another forum I frequent...

"I can get a gallon of phosphoric acid for about $7 at the local farm store. Its labeled as pipeline cleaner or milkstone remover."

I just did a search and came up with this...
http://www.tractorsupply.com/webapp/wcs/stores/servlet/ProductDisplay_10551_10001_34589_-1______?rFlag=true&cFlag=1

Guess the price has gone up a bit.

The acid is reusable, so if you can dip the parts in a pan of the stuff, you can pour the remnants back into a bottle for use at a later date.

Work good, last long time!

Hope this helps

Joe in St Louis

[jumpjg]

I did a little more research & I believe I was wrong in stating that the phosphoric acid will inhibit corrosion. The chemical I was thinking of is zinc phosphate, which uses phosphoric acid as a carrier. Metal Ready from POR-15 leaves a zinc phosphate coating, probably the Eastwood product too.

Sorry for the bum info,

Joe in St Louis

[B.O.X.N.I.F.E.]

Gibbs Brand. I've had parts of my 49 Chevy in bare metal for a couple years that still look good. No joke. I love the stuff. Also works much better than PB Blaster as a penetrating oil.

http://www.roadsters.com/gibbs/

[Mdub]

Wow I'm gonna have to get me some a dat!
Not cheap but appears to be very effective.

[mcuozzo]

I would be hesitant to put any kind of oil or petroleum based product on anything that's been sandblasted.  By sandblasting you've created a somewhat porous etched surface.  You would must likely have a hard time remove that coating completely before painting.  A smoother surface might not be as much trouble.

I've used the metal wash and I'm pretty sure it doesn't leave a zinc phosphate coating.  Zinc phosphate coatings need to be removed before powdercoating or painting.

I'll check the label next time I'm in my shop and see what it says.  And the metal wash comes as a powder and you mix it with water so I'm pretty sure it's not an acid.

[manjisann]

Thank you everyone for your responses and suggestions. It looks like the answer is really the one I was afraid of, paint withing 24 hrs of sandblasting (I read this in a motorcycle painting book, very good by Joann Bortles).

Has anyone sandblasted a frame, how long did it take you? I've come to the conclusion I'm pretty slow.

Brandon