Getting the best results from any blasting project relies on one thing: surface preparation. Whether you’re restoring a classic car chassis, cleaning heavy machinery, or preparing a steel structure for re-coating, nailing the surface preparation for blasting is a non-negotiable item on the agenda.
Take it from us: no coating, primer, or finish can make up for a poorly-prepared surface. In fact, around half of blasting and coating failures can be traced back to this single stage. It’s why we are so careful with our surface preparation for blasting as part of our work.
This guide will take you step-by-step through the protocol we follow for surface preparation to make sure it gets done right. These principles can apply if you are working with smaller DIY blasting, and if you bring us on-site for a larger restoration, you’ll also notice us going through this process.
So, let’s dive in!
Step 1: Always assess the surface.
Every successful job starts with understanding what you’re working with. Take a close look at the material, whether it’s steel, aluminium, or concrete, and note the level of corrosion or contamination. Identify any areas that shouldn’t be blasted (things like seals, glass, wiring, or labels).
That quick inspection tells you almost everything you need to know about what blasting method and media to use. It’s the first and most often overlooked stage of professional surface preparation for blasting.
Step 2: Clear and protect the area.
Before the blasting starts, make sure the workspace is clean, organised, and safe. Move tools and equipment out of the way, and cover anything nearby that doesn’t need blasting. Mask sensitive components such as windows, rubber seals, and trim if you’re working on a vehicle, or bearings.
We often work on industrial gear, so we also trim out electrical panels to prevent media from damaging sensitive electrical work. This simple step saves us a lot of time later and ensures the only thing getting blasted is what’s meant to be.
Step 3: Degrease and clean the surface.
Blasting removes coatings, rust, and scale, but it won’t get rid of oil or grease. Those contaminants only smear across the surface if they’re not dealt with first. We use an industrial degreaser or solvent wash to remove them, then wipe everything down until the surface feels clean and dry. If you’re tackling a smaller project on your own, we definitely recommend taking this step.
On machinery or older vehicles, we also make sure to spend a bit of extra time on welds, joints, and corners where oil builds up. Clean metal blasts faster, more evenly, and gives a smoother final finish.
Step 4: Choose the right blasting media.
The goal of surface preparation for blasting is to create the right surface profile, which essentially means creating enough texture for coatings to bond securely without damaging the material underneath. This means that different projects – and thus, different surface materials – will need different abrasives.
We work with garnet, glass beads, grit, vapour, and other materials for a wide range of applications. Generally speaking, heavier steel work often calls for steel grit or shot, while aluminium or stainless steel usually benefits from a firm polish with glass bead. Garnet is a versatile, eco-friendly option for both steel and concrete, and we reach for this option often.
For the more delicate jobs like restoring vintage automotive panels or soft alloys, we often reach for vapour blasting to cushion the abrasive media and prevent severe scratching.
As professionals, we always make sure to match the media and air pressure to the job, rather than relying on a single setup for everything.
Step 5: Check for moisture and contaminants.
When it comes to standard cleaning, moisture is generally quite helpful. But when it comes to surface preparation for blasting, moisture is ironically the enemy. Even a small amount can cause flash rust in mere minutes, which is why both the blasting equipment and the surface need to be completely dry before we begin.
If you’re tackling this yourself, time your work for a dry day or use a dehumidifier setup to control the humidity in the environment. A dry, clean environment will ensure your surface stays ready for coating as soon as the blasting is done.
With these guidelines for surface preparation for blasting, you’re ready to go! Remember, even the most experienced crews can overlook small details that will cost time later. If you’re tackling any part of this process by yourself, remember the golden rules: don’t blast over contaminants, don’t reuse contaminated media, and never leave an uncoated surface overnight.
Should you take one thing away from this guide, let it be this: great finishes don’t happen by chance. Everything starts with careful, consistent surface preparation for blasting, so it’s worth the time it takes to assess, clean, and set up properly.
And if you’d rather have a specialist handle the full process, we’re here to help.
Call in Hamilton Blast & Paint for professional-grade surface blasting.
From cleaning to post-blast coating, our team is equipped to do it right. Hamilton Blast & Paint works with fabricators, restorers, and industrial operators across the Waikato region, delivering precision blasting and lasting results.
Get in touch to discuss your project, and we’ll make sure your next blast starts on the perfect surface!