Water blasting or abrasive blasting for steel surface preparation?
Choose the preparation method from the coating specification and the condition of the steel. Water-only blasting can remove existing coatings and contamination while exposing an existing surface profile. Abrasive blasting can create a profile. These are different capabilities, and the surface must satisfy the specified coating system before painting proceeds. AMPP waterjet and wet-abrasive guidance
Does water blasting create the roughness a coating needs?
Water-only jetting does not create a new anchor profile in steel. It can expose a profile that was already present beneath the coating, so the condition of that profile matters. Hempel identifies this as an important limitation in maintenance preparation. Water with added abrasive is a separate method and can provide both cleaning and profile. Do not use the terms interchangeably when requesting a quotation. Hempel wet surface-preparation guideline
When should abrasive blasting remain in the comparison?
Keep it in the comparison when the steel needs a specified new profile or when the coating manufacturer's preparation requirements call for it. The proposed method must address the actual substrate, existing coating and intended service. For example, Jotun's Penguard EXA II application guide qualifies waterjet preparation by the existing roughness and specifies preparation and flash-rust requirements for that product. Its acceptance values belong to that system; they should not be copied into every project. Jotun Penguard EXA II application guide
What changes in the waste and containment plan?
Water-only preparation introduces no blasting abrasive, but removed coating and contamination still have to be collected. Water and debris can form a waste stream requiring its own handling plan. Dry abrasive work introduces spent abrasive as well as removed material. The US OSHA technical manual describes water capture and wet-debris handling as practical considerations for wet preparation. That comparison concerns the method, not a determination of the waste classification for a Philippine project. OSHA technical manual
How is water-blasted steel accepted before painting?
Specify cleanliness, profile requirements, contaminant checks and allowable flash rust with the coating supplier and responsible inspector. AMPP treats surface cleanliness, nonvisible contaminants and profile as distinct preparation subjects. A clean-looking surface alone does not answer all three questions. Hempel also distinguishes checking the cleaned surface from checking flash rust shortly before coating. The inspection plan should preserve that distinction. AMPP surface-preparation scope, Hempel inspection guidance
What information will help Dezu recommend a method?
Send photographs, the steel asset and location, existing coating information, the proposed coating system, the area to be prepared and the working window. Include access and containment constraints. A method review can then address preparation, evidence and handover together.
Dezu provides Hydro Blasting and Ship Hull and Deck Blasting. Selection remains scope-specific. A waterjet proposal should not promise a new steel profile, unconditional coating acceptance or the elimination of site hazards.
Have a scope to review?
Send the asset, condition, access and required window. Include the result the next team needs to accept.