Wet Blasting vs Dry Blasting

Wet blasting and dry blasting are two cleaning methods that entail thrusting little particles at a surface at great velocity to strip away old coatings, rust, and contaminants from a substrate. Both are basic forms of surface preparation and cleaning.

When it comes to the best blasting technique for the task, there are a few variables to consider such as desired surface finish and media type.

What is Dry Blasting?

Dry blasting, also known as abrasive blasting, is a surface finishing technique where abrasive materials are propelled at high velocity onto a surface using compressed air. This process efficiently cleans, prepares, or refinishes surfaces by removing contaminants, rust, and old coatings. 

Despite generating a lot of dust, dry blasting is highly favored for its versatility and suitability for a wide range of industrial applications, including cleaning, surface preparation, and restoration tasks.

Dry blasting can use two types of abrasive media, reclaimable and expendable. Using dry blasting equipment with expendable abrasives has a lower initial cost and is favoured for blasting outside, for instance, cleaning masonry. However, these costs can quickly mount, and blasting outside requires lots of preparation to mitigate dust egress into the wider environment.

Dry blasting utilising reclaimable abrasives has higher initial costs, but over an extended period, it provides significant cost savings. Dry blasting with reclaimable media occurs exclusively inside a slightly negatively pressured enclosure, which draws airborne particulate out of the atmosphere to filtration units, where it is captured and can be disposed of easily. The abrasive, once used, can be reclaimed and used again inside this closed-looped system.

Applications of Dry Blasting

Dry blasting is excellent for pieces that require a good amount of force, control, and speed such as:

• Getting rid of mill scale, paint, rust, and carbon 
• Plastic mold cleaning, retexturing, and de-slashing
• Glass etching, engraving, and decorating
• Surface prep for protective coatings
• Deburring and peening

Benefits of Dry Blasting

Dry blasting is a frequently used blasting technique for several applications due to its: 

Vast range of blasting materials – Dry blasting can handle practically any sort of media blast without the danger of rusting or corroding. 

Forceful blasting action – With no restrictions, the blast media stream could be thrust at a high velocity onto the worksurface, resulting in quicker cleaning times. 

Cost-effectiveness – The cost of dry blasting equipment is typically lower than that of wet blasting equipment. Dry blasting equipment uses the simple technology of mixing abrasive media and air. Dry blasting is less pricey since it doesn’t require more equipment or the disposal of water.

Versatility – Dry blasting equipment is fitting for a huge range of applications from surface preparation to high-volume production. Dry blasting necessitates less preparation, and tools, and may be done in a huge number of locations. If dust is an issue, containment, and extraction with the use of a temporary blast room could be considered.

Ability to recycle abrasive media – If the dry blasting process is done in a blast room with reclaimable media and recovery systems set up, the abrasive media could be recycled. 

Decrease the danger of flash rust – Since the process doesn’t use water, it decreases the danger of flash rust forming on steel surfaces.

Effectiveness – Dry blasting is a highly effective way of taking off corrosion, old coatings, and other impurities from surfaces. It’s important to note that dry blasting might not eliminate all soluble salts in really corroded surfaces and the surface might need to be examined for residual contaminants. 

What is Wet Blasting?

Wet blasting is comparable to dry blasting but includes the extra component of water along with air and the abrasive media. The water and abrasive media are combined to create a slurry that is thrust on a work surface using top-velocity compressed air. The pressure in the vessel is about the same as the blast hose. A flow valve between the mixing chamber controls and the hopper regulates the abrasive flow.

One of the key benefits of wet blasting is that it creates an evener finish because the water cleans away dust and abrasive residues upon contact and stops them from becoming caked in the surface.

The abrasive and water combination is usually kept propelling while the blaster is on for fast blasting action. The media abrasive and water ratio must be kept whole by removing unnecessary amounts of water from the combination. Wet blasting is a chosen process for several reasons including:

• The slurry softens the procedure, eliminating entrenched abrasives.
• Finer finishes could be done with wet blasting.
• Parts may be loaded with grease and oil.
• Water aids in eliminating oils and grease from surfaces.
• Oil may be removed from the system with a possible oil separator.
• Heat may be put into a system to quicken cleaning.
• The ability to wet blast and rinse components in one system.
• Wet blast rooms offer closed-loop procedures and clean water for rinsing.
• Wet blasting can consume up to 50% less blast media compared to dry blasting.
• Smaller footprint thanks to no dust collection
• No static

Applications for Wet Blasting

Wet blasting equipment is good for applications such as: 

• Eliminating scale, paint, carbon, rust, and other deposits
• In high-traffic areas (pedestrians)
• Where encapsulation of dust isn’t possible
• Re-painting, re-coating, and prepping surfaces before bonding 
• Stainless steel and other metals with a satin, smooth finish
• Dies and molds cleaning
• Cleaning medical aviation components
• Eliminating little burrs from manufacturing parts

Benefits of Using Wet Blasting

Dust-free – The most noteworthy benefit of wet blasting is nearly dust-free. Because of the use of water, wet blasting decreases the amount of dust generated by the abrasive blasting procedure. It is a major benefit of wet blasting. It safeguards the operative, nearby working parties, and any dust-sensitive foliage from airborne fine abrasive particles and is mostly beneficial in open environments.

Wet blasting utilizes water to remove deposits, leading to a significantly less dusty process compared to dry blasting. Also, the water cushions the abrasive media’s effect onto the work surface, stopping the media from breaking into dust.

No static charge or friction – There is a reduced danger of explosions and sparks where combustible materials and gasses are nearby. Abrasive blasting could create sparking, which can generate fires and explosions. Wet blasting does not fully get rid of sparks, but does create ‘cold’ sparks, basically eliminating the static and therefore lessening the danger of explosion.

Water dissolves the accumulation of static electricity. Wet blasting does not totally eliminate static charges, but it produces cold charges instead of sparks, removing the danger of an explosion or fire in places where dust or gasses are present.

Feathered effect – Wet blasting offers an even feathered effect where the current coating mixes with the new coating. The existence of water signifies that there is additional mass at the place of impact. This indicates that you might need a reduced amount of abrasive. These forces also offer a proper feathered edge where the new coating interacts with the current coating.

Flexibility – Wet blasting may be used on almost any surface such as thin metal. It considerably decreases the chance of warping. 

Cleaning – Another benefit to wet blasting is that the surface may be rinsed to fully clean any contamination or residual paint before putting on a coating. With some forms of wet blasting, you could remove the surface and clean it simultaneously. This removes the need for a separate rinsing procedure to eliminate media pieces.

Cost-effective – Although somewhat more time-consuming than dry blasting, the wet blasting technique uses a smaller amount of compressed air and abrasive media.

Fine abrasive media – Water is the ideal carrier for fine abrasive media. Therefore, wet blasting is typically favored when the application includes fine abrasive media.

Softer finish on many surfaces – The water functions as a cushion to diminish the impact of the abrasive media onto the work item, cleansing away the media particles, and causing a satin, smooth finish. In other forms of blasting, the effect is typically more forceful and media particles can infuse themselves into the blasted surface, creating a coarser finish. Wet blasting is frequently chosen to clean the surfaces of softer materials that must be preserved, like soft aluminum and plastic.

Degreasing functions – While oily and greasy pollutants taken away from the surface mix with dry abrasive and might create rust or blockage in crucial parts of the dry blasting machinery, wet blasting is created to endure wet contaminants and could be efficient when cleaning parts are partially oily or greasy. This removes an additional cleaning procedure and heightens productivity in some applications, which is why wet blasting is typically used to refurbish compressor parts and motors.

Find Out More

At Airblast AFC, we help our clients choose the right blast machines and blast rooms for their businesses, assisting them in creating facilities that deliver functionality and effectiveness. Please contact us today and our engineers will advise you on the best solution for your surface preparation needs.