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2 pack - alternative to grit


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I am considering having the 2 pack epoxy system for our NB Hull.  I have read that there is a new process whereby an alternative product to grit/sand is used in the blasting process which is kinder to the hull.  Due to my cognitive issue I cannot remember where I read about it, what it is called and which company offers this service.  I know debdale marina use the grit blasting process and spray molten metal.

can anyone assist with refreshing my memory and any other views on my thoughts?

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Dry ice blasting is a cleaner way of blasting, as the dry ice (CO2) evaporates and thus unlike grit doesn't require cleaning up, but probaby adds to global warming instead.

However the rust and paint it removes won't evaporate so there will still need some clearing up required afterwards.

https://www.optimumdryiceblasting.co.uk

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There are more blast media than you can shake a hairy stick at, and all in various grades and sizes.  Which one to use depends on the job and what you want out of it.  More or less anything which can be blasted will work in the end but time is money so it is a balance between cost of material,  time taken and the finish needed (usuall SA2.5 for mild steel).  The kit available also has to suit the media.  Crushed glass, copper slag and chill cast iron grit are alll  reasonably priced and pretty effective so are common media for rusty steel.   Sand is cheap and effective but has the H&S  folks doing bunny hops because of the dangers of silicosis. Carbide grit is good, but dear and so it goes on.

Plain water at seriously high pressures ( 40,000 psi up) is very effective but the kit is expensive and the protective gear is like an armoured spacesuit.

Walnut shells tend to be suited to more delicate substances- like gas turbine engine compressor blades.  Dry ice needs some methpod of producing it. 

Blast cleaning is a big subject!

 

N

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When plastic ic chips had little legs they used walnut shell to remove the plastic encapsulation flash from the legs as it is too soft to remove the gold or tin plate on the legs.  So you need a blast media that is hard enough to shift rust.

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3 hours ago, BEngo said:

There are more blast media than you can shake a hairy stick at, and all in various grades and sizes.  Which one to use depends on the job and what you want out of it.  More or less anything which can be blasted will work in the end but time is money so it is a balance between cost of material,  time taken and the finish needed (usuall SA2.5 for mild steel).  The kit available also has to suit the media.  Crushed glass, copper slag and chill cast iron grit are alll  reasonably priced and pretty effective so are common media for rusty steel.   Sand is cheap and effective but has the H&S  folks doing bunny hops because of the dangers of silicosis. Carbide grit is good, but dear and so it goes on.

Plain water at seriously high pressures ( 40,000 psi up) is very effective but the kit is expensive and the protective gear is like an armoured spacesuit.

Walnut shells tend to be suited to more delicate substances- like gas turbine engine compressor blades.  Dry ice needs some methpod of producing it. 

Blast cleaning is a big subject!

 

N

We use to use the nut shells in our Gas Turbine Ruston generators, The whole platform smelt wonderful, but you were in trouble if you forgot to inhibit the smoke detection. We use to feed it into the air inlet with the generator running on no load

 

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4 hours ago, cuthound said:

Dry ice blasting is a cleaner way of blasting, as the dry ice (CO2) evaporates and thus unlike grit doesn't require cleaning up, but probaby adds to global warming instead.

However the rust and paint it removes won't evaporate so there will still need some clearing up required afterwards.

https://www.optimumdryiceblasting.co.uk

I’ve seen (on TV) dry ice used for blasting old oak beams in a barn conversion. It did a stunning job of cleaning the wood without either wetting it or leaving embedded metal particles. Don’t really see the point on a rusty, pitted steel hull though. 

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I would leave the decision on how to blast down to yard doing the work as they will know how to do it. Grit blasting will give you SA2.5 (which as Bengo said is the standard needed). This is the standard all paint suppliers will aim for. Choose a yard that will get to that surface standard - and you will have a better chance of getting a good job done. If they dont achieve that standard then there is a good chance you will get a paint job that will not perform the way it was designed.

  • Greenie 1
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