We are often asked about the advantages and disadvantages of dry ice blasting compared to soda blasting, or abrasive blasting in general, so let's take a close look at dry ice blasting.
What exactly is dry ice? Dry ice is the solid form of carbon dioxide and is considered a hazardous material; therefore, precautions must be taken when using dry ice for blasting.
Dry ice blasting is a process where dry ice pellets are accelerated by compressed air to high speeds that fracture the top layer of dirt and residue then, once the dry ice penetrates the dirt and residue, the temperature of both the dirt and residue layer and the substrate decreases. The different materials contract unequally and the adherence between them decreases. This temperature difference helps to separate the dirt and residue from the substrate. After the dry ice makes its initial impact, it instantly turns from a solid to a gas. The volume expansion causes a micro explosion that detaches the dirt and residue from the substrate, leaving it clean and dry. This is similar to soda blasting.
Dry ice, although not technically harder than baking soda, will cause surface damage to wood structures because of the high velocity it requires in order to work effectively. Dry ice can also cause an exothermic reaction on layered substrates, causing failure or damage. For example, printing rollers found on printing presses should never be blasted with dry ice, as the ceramic top coat of the roller will peel away from the steel core it is bonded to when subjected to severe temperature changes. Additionally, only baking soda deodorizes the surrounding indoor environment. This is especially important when doing fire restoration work, as you want the soda dust to travel where the smoke went in order to completely eliminate any trace odors. When doing a fire job with dry ice, the end result may look the same, but it will not smell the same.
On the production side looking on a per square foot basis, coverage rates for soda blasting and dry ice blasting are about the same; however, dry ice blast hoses are shorter in length (usually only 40’ long compared to up to 200’ for soda blasting). The short dry ice blast hose is necessary to prevent further melting of the material and also minimizes the freezing effect. The short hose also means more time is spent moving equipment around versus time spent blasting. As for the media, dry ice will last approximately 2-5 days, and is subject to sublimation (melting) from the moment it gets shipped to the job site. The longer the transit time, the shorter the shelf life. All other blast medias, if stored properly, can last for years. Also keep in mind that large amounts of dry ice are heavy and bulky, and usually require a fork lift and loading dock or lift gate at the job site. For hotter climates, indoor storage during the project is recommended.
There are also worker concerns to consider when using dry ice blasting. Dry ice literally sucks the oxygen out of any enclosed space, so wearing a proper tethered hood system is a must (see links above for hazardous material warnings of carbon dioxide). For semi-ventilated areas, an oxygen level monitor is usually needed. Special Personal Protection Equipment (PPE) is also required when filling the pressure vessel with dry ice (baking soda, as well as many other types of media, can be handled with bare hands, and does not require special PPE when filling the pot, etc.). Most dry ice blasters are more fatigued at the end of the day when compared to other blasting methods as well.
Kelso Restoration has the knowledge and experience to identify the appropriate blasting method and media for your job and we will get your project done right the first time. With offices in Milton and Ottawa, we are happy to service not only the Greater Toronto area and eastern Ontario, but also the entire of Ontario and beyond. Give us a call today.
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