Wet Blasting: Thickness, Specs & Materials

What is Wet blast?

The water cushions impact, suppresses dust, and generally produces a finer appearance than comparable dry grit blasting.

How it works

A pump mixes water, fine abrasive, and optional compound into a slurry that compressed air accelerates through a nozzle. Fine glass bead or alumina cleans while the liquid cushions impact and flushes debris. Typical resulting Ra is about 0.8–3.2 µm (32–125 µin). Media chemistry, 100–220 grit or equivalent size, pressure, corrosion inhibitor, rinse quality, and drying determine the final condition.

Why specify it

Produces Ra about 0.8–3.2 µm (32–125 µin)
Suppresses airborne dust
Gives a fine uniform satin surface
Reduces heat and impact severity versus dry blasting

Where it falls short

Can still round edges and alter texture
Poor rinsing leaves residue
Carbon steel can flash-rust after rinsing
Media embedment risk is reduced but not eliminated

Wet blast at a glance

Wet blast is strongest on cosmetic quality (70 of 100), at a standard cost. It adds little corrosion protection. Surface hardness is not rated: the finish leaves the part's own surface.

Corrosion protectionMinimal5 / 100

Surface hardnessNot rated—

Cosmetic qualityVery good70 / 100

LubricityLow15 / 100

Relative costStandard30 / 100

Each score is 0–100 against every finish in this catalog. Corrosion comes from salt-spray life (ASTM B117, log scale) and hardness from the finish layer's Vickers or pencil hardness; cosmetic, lubricity and cost are FabDigit's engineering assessment. Economy on the radar is the inverse of cost.

Wet blast key numbers

Typical values from the governing specifications and shop practice; bars are this finish against the highest value among mechanical finishing finishes.

Thickness0 µm0 mil

Thickness: No coating; typical resulting Ra 0.8–3.2 µm (32–125 µin).
Electrical: Unchanged
Appearance: Fine, uniform, low-glare satin surface.

Specifications for Wet blast

The documents a drawing cites to define this finish, with the Type / Class rows that apply. Each links to a page explaining the standard.

Drawing call-out

WET BLAST ALL EXTERNAL SURFACES WITH 180 GRIT ALUMINUM OXIDE SLURRY TO Ra 1.6 µm MAX; MASK DATUMS, THREADS, AND SEALING FACES

Which materials take Wet blast?

Verdict per material family, with the grades that behave differently. Each family links to its datasheets in the material library.

Material family	Verdict	Notes
Aluminum	Yes	Common for a fine satin casting or machined appearance.
Brass	Yes	Suitable; protect against smear and media embedment.
Copper Alloy	Yes	Suitable; expect faster cutting and easier smearing than steel.
Stainless Steel	Yes	Use clean dedicated media and complete rinsing.
Titanium	Yes	Common fine satin blast with iron-free media.
Magnesium Alloy	With care	Possible with non-sparking media and fire-safe dust control.
Polymer	With care	Only rigid compatible polymers tolerate useful slurry abrasion.
Steel	With care	Flash-rust control and immediate drying are required.
Zinc Alloy	With care	Soft die-cast zinc cuts quickly and can embed media.

How Wet blast is applied, and what it does to the part

1Degrease
2Mask
3Wet blast with specified fine media
4Rinse thoroughly
5Dry immediately and inspect

Dimensions	Bulk removal is normally low, but precision surfaces and sharp edges can change with pressure and dwell; mask them.
Build-up per side	0 µm — No buildup; bulk removal is low but process-dependent.
Masking	Usually needed. Mask fits, sealing surfaces, threads, labels, and cavities that cannot be fully rinsed and dried.
Electrical	Unchanged
Appearance	Fine, uniform, low-glare satin surface.
Added lead time	1–4 working days on top of the bare part

Design rules for Wet blast

What to decide on the drawing before the part goes to the finisher.

Specify media and size.Fine glass bead and alumina produce different cut and gloss.
Require rinse and dry.Residue and trapped water can contaminate or corrode parts.
Mask precision faces.Low removal is not zero removal.
Use an approved sample.Slurry concentration and pressure change satin appearance.

Wet blast versus the alternatives

Finishes engineers weigh against Wet blast, and when each wins.

Finish	Corrosion	Hardness	Cosmetic	Cost	Choose it when
Wet blast this page	5	—	70	$$	—
Bead Blasting Wet blast vs Bead Blasting →	5	—	65	$	when a dry glass-bead cosmetic process is acceptable
Sand Blasting Wet blast vs Sand Blasting →	0	—	35	$	when aggressive scale removal is required

Wet blastBead Blasting

The radar overlays Wet blast with Bead Blasting, its most common alternative — chosen when a dry glass-bead cosmetic process is acceptable. Scores in the table are 0–100 across every finish in the catalog.

Cost, lead time and compliance

Relative cost

Wet Blasting is a standard-cost finish ($$): cheaper than about 67 % of the finishes FabDigit quotes.

Finishing is priced per part with a lot minimum, from FabDigit's own China-side rates. The exact figure appears on the instant quote once the part is uploaded.

Lead time and compliance

Added lead time	1–4 working days
RoHS	Compliant
Notes	Treat slurry and removed contaminants; closed-loop systems reduce water use.

What Wet blast is used for

Aluminum castings
Stainless fluid components
Restored machine parts
Medical instrument housings

Wet blast — frequently asked

wet blasting vs vapor blasting

They are commonly used as synonymous terms for slurry blasting. Both combine water and abrasive to produce a fine satin surface with less airborne dust than dry blasting.

what Ra does vapor honing produce

Typical controlled results are about Ra 0.8–3.2 µm (32–125 µin). Media size, pressure, dwell, and starting surface control the actual value.

does wet blasting embed grit

The water cushion and flushing can reduce embedment risk, but do not guarantee zero embedded media. Use compatible dedicated media and validate cleaning for critical parts.

can wet blasting rust steel

Carbon steel can flash-rust after rinsing. Use compatible inhibitor where allowed and dry immediately before the next protective operation.

wet blast vs bead blast

Wet blasting suspends fine abrasive in water and commonly leaves Ra 0.8–3.2 µm. Dry glass-bead blasting is simpler but dustier and commonly leaves Ra 1.6–6.3 µm.