Anyone use dry ice sandblasting?

[Jim Mackell]

We are considering the use of dry ice blasting to remove numerous layers of paint from one of our century old wooden trolley cars. From what we have seen on various manufacturer sites, the technology seems to work well and cause no damage to the underlying wood.

http://www.archithings.com/dry-ice-blasting-lead-based-paint-from-utah-state-capitol/2008/08/10

Has anyone at the Creek has personal experience with one of these devices and would be willing to comment pro or con?

Thanks in advance!

[Van Huskey]

I don't know anything about it but looking on the manufacturers site it is very cool, explosions and shockwaves are always fun even on a micro-scale!

http://www.coldsweep.com/Coldsweep.com/Dry_Ice_Blasting.html

[Kevin Bourque]

Its truly an amazing process.
The dry ice pellets flash freeze the surface and then expand hundreds of times their original size in the blink of an eye.
The paint, rust, varnish, etc. is literally blasted off the surface.
It's not an abrasive process, but a blasting process that won't harm the substrate. You can even blast electrical equipment while it's HOT without danger of shock.
The dry ice blasting machinery can blast off the heavy encrustation on a boats anchor, or the mold off a piece of antique paper without damaging the paper or ink.
You don't need to tarp off the area you're working on like you do with sandblasting since the dry ice just evaporates into the air.

Now heres the bad news: It's VERY expensive
I forget exactly what the contractors charge, but if you are removing something difficult like several layers of paint then you will use a lot of dry ice per hour.
If I remember correctly its somewhere around 150 lbs. per hour and dry ice is about $1 or less per lb. if you buy a large quantity.

Dry ice blasting is fantastic for removing coatings on delicate surfaces, but sand or soda blasting is a much cheaper way to go if you can deal with the mess.
The guy I use for sandblasting charges $50 per hour.

[Matt Marsh]

They use one at the OSB mill that I use to work at here in northern MN. They would ship in a pallet with an insulated tub of dry ice pellets for down day once a week. They used it blast the crud from the steel press platens. Awesome for that, no debris other than the flecks of crud that was removed. No experience with using it on wood. This machine could have blasted completely through a solid piece of oak in no time flat. The worst part of using the machine was that it gave the operator holding the hose or nozzle some of the nastiest static shocks imaginable.

[Jim Neeley]

Also, use caution to ensure plenty of ventilation if you SB with dry ice. It is made by taking liquid carbon dioxide and flashing it to atmospheric pressure and then compressing the resulting "snow". <I grew up on top of a CO2 plant, which also made dry ice from the liquid CO2>. When it vaporizes, the CO2 is released into the atmosphere. While not poisonous in and of itself, it does displace oxygen in the air and can lead to people collapsing (and possibly dying) due to oxygen deprevation.

Jim

[Brian Kerley]

I remember seeing an episode of TOH where they blasted mold off of the underside of a roof by shooting the dry ice at the underlayment.

[Jim Mackell]

I remember seeing an episode of TOH where they blasted mold off of the underside of a roof by shooting the dry ice at the underlayment.

Also featured on several episodes of Holmes on Homes for mold removal.

[Carl Beckett]

I have used dry ice to debur and finish implanted medical devices.

Specialized equipment, some safety precautions, but it works great.

I dont understand the claim that it doesnt damage the underlying wood. In the solid form, its an abrasive like any other. Yes it heats and evaporates away, but the process is still 'grit' blasting at the fundamental level.

[Jim Mackell]

I dont understand the claim that it doesnt damage the underlying wood. In the solid form, its an abrasive like any other. Yes it heats and evaporates away, but the process is still 'grit' blasting at the fundamental level.

The explanation that I have read is that the solid CO particles "explode" and convert into their gaseous form on impact. The paint is blown away because the impact fractures the surface sheen. The video of the paint stripping in Utah seems to show no damage at all to the underlying woodwork.

That's what I'm hoping to be able to confirm by someones personal experience.

[Carl Beckett]

The explanation that I have read is that the solid CO particles "explode" and convert into their gaseous form on impact. The paint is blown away because the impact fractures the surface sheen. The video of the paint stripping in Utah seems to show no damage at all to the underlying woodwork.

That's what I'm hoping to be able to confirm by someones personal experience.

I havent tried it for paint removal, so cant comment.

[Chad Bender]

Astronomical observatories routinely use it to clean telescope mirrors. Large facilities (Keck, HET, probably others) use it on a near daily basis to remove dust and dirt. No damage to the mirror coating occurs, so I suspect it's pretty safe.