Blasting off boats - antifouling, bilges etc - CO2 Dry Ice?

[AntarcticPilot]

Don't use sand on your cast iron keel use grit it gives a much better (rougher) surface that holds the epoxy paint primer better.

I may be being dense here, but what's the difference? I use the terms "sand" and "grit" interchangeably. Is the grit corundum (which I'd have imagined would be prohibitively expensive) or is it quartz?

 

[rogerthebodger]

Grit is much harder than sand and the shape tends to be more angular so it makes a rougher surface for the paint to get a better grip.

think of the difference between rough sand and the grit you get on rough emery cloth.

When I grit blasted my steel boat I used crushed slag but I don't think you get much slag in the UK now.

 

[vyv_cox]

I think you will find it is illegal to blast with sand in UK, only quoting what I have read. Aluminium oxide is recognised as the superior blast medium, giving an excellent finish for overpainting.

 

[Twister_Ken]

The guys that did mine used crushed lava. Seemed to do the trick but no cast iron on a Twister.

 

[JumbleDuck]

I think you will find it is illegal to blast with sand in UK, only quoting what I have read. Aluminium oxide is recognised as the superior blast medium, giving an excellent finish for overpainting.

http://www.hse.gov.uk/press\2008/coinw01708.htm

 

[AntarcticPilot]

http://www.hse.gov.uk/press%5C2008/coinw01708.htm

That's OK, then. The kit I'm looking at is wet blasting, not dry.

 

[smeaks]

That's OK, then. The kit I'm looking at is wet blasting, not dry.

If you are blasting AF remeber the resulting dust is nasty so wet is good. You can use many medias and one such is glass AF glass measures 74-149 micron and will mix well with the wet blast to slurry blast. When you do it start on the keel and play with the air pressure/media feed and duration until yopu get the desired removal and then move onto the hull.

If using dry you can get blast/suction kit that will recirc media and should lift out the debris and dust.

 

[Elessar]

The guys that did mine used crushed lava. Seemed to do the trick but no cast iron on a Twister.

We used to use crushed lava but now use crushed, recycled glass bottles. Ordinary sand is illegal if used dry and we never buy it.
The abrasive is like sandpaper, you can have different particle sizes.
For steel you can use a more aggressive media if you wish.