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What is Sweep blasting?

October 19, 2008

Q. My name is Sreejith. I am working in a aluminium and steel fabrication company as a quality controller. I want to do painting on some steel fabricated items. The pretreatment given:
1. sand blasting
2. hot dip galvanising
3. sweet blasting
4. painting. I want to know, is this much preparation before painting necessary? (structural steel items)
5. What is sweet blasting?

Sreejith M.N.
quality controller - Dubai, UAE

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Ed. note: We changed the title of this inquiry to "Sweep Blasting" after reading Geoff Crowley's response below

December 11, 2008
A. Someone has given you poor information.
1. You don't need to shotblast if you intend to galvanize the steel unless it has previously been painted. If it's new steel, it needs no blasting to galvanize it.
2. Galvanizing is a corrosion protection. If protection is what you need, then you don't need to paint it. If you need a special colour, or a highly aesthetic finish then you could paint.
3. There is no such thing as "sweet" blasting. There is "sweep" blasting. (could be a typo?). This means a very light blast by "sweeping" the nozzle over the work. It means a very light blast. Its a poor pretreatment method for preparing galvanized steel for painting. It's expensive, messy and ineffective.
4. Painting. You can paint steel that has been blasted but not galvanized. In this case, shotblast, prime, paint. If the steel has been galvanized, then you need a pretreatment or the paint will not adhere properly. There are a number of proprietary brane chemical pretreatment systems available. You apply (spray or brush apply) the pretreatment, then after drying you paint.

Good luck, hope you get a "sweet" job.

Geoff Crowley
galvanizing &
powder coating shop
Glasgow, Scotland

January 26, 2012 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. What would be the surface profile for sweep blasting the stainless steel substrate, and what should be nozzle pressure?

Mahesh sk
- Doha, Qatar

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