Wet Blasting VS Water Jetting Vs Pressure Washing
As a paint contractor you often will need to properly prepare your surface to ensure your coating adheres well and performs as well as the coating manufacturer states. Choosing wet blasting, water jetting, or pressure washing will depend on your application and the desired preparation you are trying to achieve.
Water Jetting
Water Jetting is similar to pressure washing but is performed at extraordinarily high pressures (above 10,000 PSI). If the pressure is below 10,000 psi it is typically considered pressure washing or also known as water cleaning. Due to the high pressures used by water jetting, it is sufficient to clean a product in accordance with SSPC-SP12 or NACE 5 standards. Within the standard your coatings provider should specify the recommended visual as well as non visual level of cleanliness. Visual levels of cleanliness are covered by SSPC WJ 1 – WJ 4. Non Visual levels of cleanliness are determined by a different set of standards that your coatings provider should be able to help with. The primary difference between water jetting and pressure washing is that the higher pressures will better allow removal of loose mill scale and similar adhering surface contaminant allowing you to re expose the original substrate. This can provide a much better profile for the coating to adhere to in comparison to pressure washing which will primarily only remove non adhering contaminant like dirt.
Pressure Washing
Pressure Washing is considered using pressure less than 10,000 PSI. With the low pressure it is not sufficient to remove all contaminants and cannot be used for SSPC 12/ NACE 5 Standards. This makes pressure washing mostly useful for general surface cleaning prior to potential painting.
Wet Blasting
Wet blasting is a form of Blasting that also incorporates water into the blast media stream. There are a variety of advantages and drawbacks to wet blasting. In general wet blasting allows you to create a profile on a product which is important if your dealing with a surface that has a significant amount of coatings on it or needs a profile and doesn’t currently have one. Profiles with wet abrasive blasting will be similar to dry blasting but will also often have a layer of flash rust because you are using water to convey the media to the surface of the product. The flash rust can be mitigated by using a rust preventer. Standards for creating profiles with wet blasting fall under SSPC 5,6,7,10,14 and NACE WAB 1,2,3,4,8 which you can learn more about the standards through SSPC. If your product has never been prepped before and your paint provider requires a profile you will have to consider dry blasting or wet blasting. The primary benefit to wet blasting is that it can help control dust but it does have challenges due to the flash rust that can be created. It can also help clean off abrasive dust after blasting but this can potentially be accomplished with an Abrasive Cut off option on a standard blast pot. If dust is a big concern it may be the right option over dry abrasive blasting. You can also read more about the advantage and disadvantages as mentioned above to see if it makes sense for you.
Ultimately by understanding preparation standards for surfaces based on SSPC and NACE requirements you can better be prepared to select the appropriate preparation equipment solution. If you are considering wet blasting the Clemco Wetblast Flex or wet blast injector system can allow you to begin wet blasting for a reasonable cost. If you have other questions about blasting or surface preparation you can download our complete guide to blast equipment.