How to Treat Bare Metal After Media Blasting

Media blasting is one of the most effective ways to remove old paint and rust from automotive surfaces. In almost no time it can strip away unwanted finishes, dirt, and corrosion, revealing the bare metal underneath. This is a crucial step in automotive restoration as it provides a clean surface for further refinishing. However, blasting leaves behind its own residues (mostly dust) that need to be cleaned up before a new finish can be applied. It also leaves the bare metal susceptible to new corrosion if it’s not protected right away, as can happen with slow-moving restoration projects.

So what should you do once you’re done blasting? One obvious solution is to clean up the newly blasted part and refinish it immediately, sealing it with an etching primer or some other type of direct-to-metal (DTM) finish. If you can’t apply paint or primer right away, you’ll need to stabilize the bare metal while it waits to receive other work before paint. Eastwood makes two unique products are designed specifically for this – Fast Etch and the appropriately named After Blast. Both work similarly but have unique advantages depending on your project.

Fast Etch

This acid-based surface preparation  serves two functions on steel or iron parts: it dissolves rust and it leaves behind a protective phosphate coating. The first is important to ensure you’ve gotten all the rust off the metal. After all, blasting is only effective where you can aim the nozzle. Depending on your part, there may be internal surfaces that blasting can’t reach. Treating a freshly blasted past with Fast Etch finishes the job of eliminating rust in hidden spaces. The second and most obvious function is the protective zinc phosphate coating it leaves behind after treatment. The treated surface takes on a characteristic dull gray finish that provides a measure of rust prevention while the part sits in the shop or receives other work. It’s not a permanent form of rustproofing, however, so eventually you’ll need to protect the bare metal. To use Fast Etch, simply spray or bush it onto a bare metal component, wearing acid-resistant gloves and protective eyewear. You can also soak a part in a container of Fast Etch using a plastic tub. Once the rust and metal have completed their reaction – which could take as little as a few seconds for light scale or as long as several minutes for heavy rust – you can neutralize the acid and wipe off the residue using a cleaning solvent like Pre Painting Prep.

After Blast

This treatment is also an acid-based preparation solution, but adds a cleaning property as well. This product contains a degreaser plus a surfactant to help remove residual oils and other contaminants from the surface. This makes it ideal for treating oily mechanical components after blasting, especially where blasting along may not reach. Like Fast Etch, After Blast reacts with the bare metal and leaves behind a zinc phosphate coating for protection. The process is essentially the same as well and requires the use of basic personal protective equipment to prevent skin and eye damage. A solvent wipe will neutralize the treatment and leave behind a slightly smoother surface than that of Fast Etch. In both cases, the reaction slightly etches the metal surface as well, promoting adhesion with primers, paints, and other finishing products. Once again, the zinc phosphate coating provides a degree of short-term rust protection but is no substitute for a final finish, and the coating will need to be removed from any area prior to welding.