Any special prep required after sandblasting?

[ericher69]

I spray my blasted parts with southern polyurethanes wax and grease remover and wipe them off with a rag. Then i use scotch brite in one hand and an air hose in the oher to blow off the rag fuzzies. Then i spray 2 coats of southern polyurethanes epoxy primer. This holds up very well from my experience.

Sounds expensive! Don't you need supplied air to paint with polyurethanes or does ORganic Vapor cartridges cut it?

 

[strum456]

Sounds expensive! Don't you need supplied air to paint with polyurethanes or does ORganic Vapor cartridges cut it?

With proper ventillation O V cartridges will do. The stuff i use is made by a realitively small.company in georgia. It is probably the best epoxy you can buy for any dollar amount. You will be pleasantly surprised by the price too (unless you are comparing it with something like rustolium). You havent mentioned what you are painting but if it is valuable epoxy is the only product I would consider.

 

[Mace Canute]

I was wondering if any special prep/work are required after sand blasting and before priming?

In the past priming/painting after blasting has led to rust within a year!

Am I missing a step?

Any advice from pro painters would be appreciated!

Thanks

Have a read though this site about "profile".

It's one of the possible reasons for your paint job rusting so soon after it's done.

 

[Renze]

You really get what you pay for in primer. I remodel homes for a living and I'm still surprised at how many people use Kilz and then wonder why the paint doesn't go on well, or looks terrible.

Same thing with painting metal. I really like Rustolium Premium paints. They go on better and last a long time without any issues.

Very true. Some paints are allmost water, they are full of solvents but have no solids in them: When you apply a heavy coat, the solvents evaporate and you stay with a thin layer when dry.

Also if you take the time and money to sandblast, the last 5 bucks on a can of paint means nothing compared to the cost of blasting.
Some primers just eat their way into the metal and stick for decades, and some can be blown off with a pressure washer.

Not all paints/primers are equal....

oh, and to what standard does your blaster blast ?? Swedish standard SA 2.5 is what we demand from our suppliers of wheel loader frames. Sa 2 is enough for earth buckets that wear bare within a day anyways. SA 3 is a 100% equally grey surface colour without ANY impurities, its harder to achieve because the blaster usually works in a dusty environment and cant see his work in bright daylight...

 

[Hooked_on_HP]

Do you have a good water trap on your blaster. If you are useing a siphon blaster you are probably getting a lot of moisture from your air line.Siphon blasters use a lot of air. Pressure tank blasters use a lot less air. If you are blasting when it is cool out you will get a lot of condensation in the air lines. If you paint or prime over moisture it just traps it and makes rust quicker. What media are you blasting with. The coal slag they sell at menards seems to leave a greenish film that I don't like. I still like silica sand. I know you arent suspose to use it but it still gives the best results. You can still get it at menards. The call it handy sand.
Bill

 

[strum456]

I would wager that the last two posts combine explain your problem. You need enough mil thickness to burry the blast profile and and this can be hard to achieve with much of the low solids paint out there. Even if the paint says it is high solids on the can that doesnt mean it is. Unfortunately there is no standard on this and companies are free to market their paint how they want. The only oway to oknow for sure is to buy it and try it.

 

[ericher69]

Very true. Some paints are allmost water, they are full of solvents but have no solids in them: When you apply a heavy coat, the solvents evaporate and you stay with a thin layer when dry.

Also if you take the time and money to sandblast, the last 5 bucks on a can of paint means nothing compared to the cost of blasting.
Some primers just eat their way into the metal and stick for decades, and some can be blown off with a pressure washer.

Not all paints/primers are equal....

oh, and to what standard does your blaster blast ?? Swedish standard SA 2.5 is what we demand from our suppliers of wheel loader frames. Sa 2 is enough for earth buckets that wear bare within a day anyways. SA 3 is a 100% equally grey surface colour without ANY impurities, its harder to achieve because the blaster usually works in a dusty environment and cant see his work in bright daylight...

Standard? For large items I get the local large welding shop to blast

For smaller items I use my blast cabinet with silica free sand from TSC

Yes it is a syphon blaster and I have a desiccant air dryer with a filter after the dryer

 

[EastBerkshireCustoms]

I would suggest a good epoxy primer after blasting with a silica free media. Not only is silica very bad for your health, but it can leave a residue behind that paints won't adhere to.

 

[ericher69]

I would suggest a good epoxy primer after blasting with a silica free media. Not only is silica very bad for your health, but it can leave a residue behind that paints won't adhere to.

Epoxy primer ; any brands in mind?

Are these only available for spray guns or also in rattle cans?

 

[strum456]

What I suggested is epoxy primer. Southern Polyurethanes makes it. Their plant is in Blairsville Georgia. I've used epoxys from several of the major paint companies, and I like the SPI epoxy a lot better. Here are a couple pictures of a paint job I did with SPI products.