Shot Blasting
Boat Restoration
SHOT BLASTING: ESSENTIAL PREPARATION FOR LONG-LASTING PROTECTION
What is Shot Blasting?
Mill scale, a type of iron oxide formed during the hot rolling process, appears as a smooth, bluish-grey layer. While it might seem protective, mill scale is neither uniformly adhered nor durable. Left untreated, it can cause significant issues, such as:
- Coating Failure: Paint applied over mill scale often cracks and detaches, leaving the steel surface exposed.
- Accelerated Corrosion: The porous nature of mill scale allows moisture to penetrate, triggering galvanic reactions that lead to pitting corrosion.
- Structural Damage: Rust growth beneath the mill scale exacerbates cracking and spreads corrosion further.
To prevent these problems, mill scale must be completely removed to achieve a clean surface, ensuring optimal adhesion and longevity for protective coatings.
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Our Process at Bluewater Boats
At Bluewater Boats, we clean steel surfaces to an SA 2.5 profile using an abrasive blast. This process removes mill scale entirely and creates the necessary surface profile for the paint system to adhere effectively. Painting over mill scale, however tempting, is a short-term solution that accelerates corrosion and compromises the integrity of the steel.
Real-World Example: The Importance of Shot Blasting
We recently restored a narrowboat that had been painted without removing mill scale. Less than a year after its launch, the boat suffered significant rust damage both above and below the waterline. The owner brought it to us for shot blasting and repainting, and the results speak for themselves—a durable and professional finish that will stand the test of time.