The Bilt Hamber Electrox Zinc Primer 400ml is a zinc-rich primer for bare steel and welded seams. As a car zinc primer you use it where rust must not get a foothold: chassis rails, floor pans, suspension parts and welds after panel repairs. The dry film is over 90% metallic zinc and protects the steel galvanically, the same principle as hot-dip galvanising. You spray it straight from the can.
Where a zinc primer belongs on your car
Zinc keeps protecting steel even when the coating is lightly damaged: the zinc corrodes first and the steel underneath is spared. That is why restorers choose a zinc primer for places that stay wet and take a beating, such as chassis rails, floor pans, suspension components, trailers and caravans. Welds where you have exposed bare steel get a coat too. For loose parts and small repairs the aerosol is the easiest option. If there is still rust on the steel, read our guide Removing rust from your car first. You will find more products for this work in the spray can and primer category.
Key facts about Electrox
Property | Detail |
|---|---|
Brand | Bilt Hamber |
Type | Zinc-rich primer, single pack |
Content | 400 ml aerosol |
Application | Spray from the can |
Zinc content | Over 90% in the dry film (manufacturer's figure) |
Drying time | Touch dry in 20 to 30 minutes, hard dry in about 3 hours (manufacturer) |
Suitable for | Bare steel and welded seams |
How to use Electrox
Take the steel back to bare metal. Grind, blast or wire-brush until you see bare steel and remove all loose, flaking rust. The manufacturer names SA 2.5 as the ideal preparation. Tip: avoid very coarse tools, because the surface profile should not exceed 75 microns.
Degrease thoroughly. The steel must be free of grease, oil and mill scale. Wipe down with a clean, lint-free cloth and keep bare fingers off the metal afterwards.
Protect your surroundings. Tape off paint and rubber seals and cover anything that should not get primer. Work in a well-ventilated space and wear suitable protection, because the overspray travels.
Shake and spray. Shake the can well so the zinc powder mixes in, and shake again now and then. Spray one full, even coat and do not go back over it while it is still wet. Tip: include edges and welds, because that is where rust starts first.
Let the coat dry. According to the manufacturer it is touch dry after 20 to 30 minutes and hard dry after about 3 hours. For heavy-duty use, such as marine work or a chassis that lives outdoors all year, the manufacturer recommends a second coat. As a guide, allow 2 to 3 hours before applying it.
Overcoat or leave as it is. You can paint over a hard dry coat. If your topcoat uses strong solvents, wait 24 to 96 hours (the longer time if in doubt) and test on a small patch first. Where stone chips will hit the surface, add a stone chip protection over the top.
Common mistakes and tips
Spraying too early on steel that still carries grease or dust: the coat bonds worse than it should.
Not shaking the can: zinc is heavy and settles, so shake during spraying too.
Building the coat too thick, or going over the same spot repeatedly: one full coat is enough, a second coat comes after drying.
Skipping edges and welds: that is exactly where rust starts, so cover them well.
Putting a strong topcoat over a freshly cured primer: wait the stated time and test on a small area.
What to combine Electrox with
A zinc primer is one part of rust prevention. The rest of the system is covered in our guide Rust prevention and underbody protection. Useful additions:
Bilt Hamber Hydrate 80: water-based rust converter, for areas where you want to convert rust instead of grinding it back. See also our guide Using Hydrate 80.
Motip Anti-Gravel Underbody Protection White: brush-on stone chip protection for the underside of the car.
Bilt Hamber Atom-Mac Corrosion Inhibitor: vapour-phase corrosion inhibitor for cavities, underbody and suspension.