Surface preparation before plating: good plating starts before the bath
A large share of peeling, darkening, dullness and adhesion problems comes from surface preparation. Anyone experienced in plating knows that a good finish is usually won before the part ever reaches the plating tank.
Why surface preparation is so critical
If a part carries oil, oxide, rust, weld marks, polishing residue, burrs or surface dirt, even the best plating bath cannot deliver the required result on its own. Metal can look clean to the eye and still carry microscopic oil, oxide or dirt that stops the coating from bonding fully to the base metal.
The part may look good when it leaves the line, yet over time it can peel, blister, stain, darken or turn dull. On decorative work this matters even more: on bright nickel, chrome, gold or smoked surfaces, the smallest defect becomes visible.
Degreasing
Degreasing is one of the most important steps before plating. Parts arriving from production may carry press oil, cutting fluid, polishing compound or oil from handling. Plating over this film cannot bond properly to the surface.
The degreasing route should be chosen according to the part’s material, its surface condition and the type of contamination. Not every part carries the same dirt, so applying one recipe to every part is not the right approach.
Activation
After degreasing and rinsing, the surface is activated so that it is ready to plate. Activation removes the thin oxide layer on the metal and prepares the surface for the plating bath.
Time and chemical balance are critical. If a part stays in activation too long, the surface can darken, over-etch or react in unwanted ways; too short, and it may not become active enough. Activation is done with the right time and process knowledge, not on a “longer is better” basis.
Where most plating defects begin
Much of the peeling, darkening, blistering, dullness or staining starts before the plating bath: when the surface is not clean enough, the oxide is not fully removed, rinsing is weak or the part waits too long between tanks.
That is why judging plating quality by the final look alone is not enough. Degreasing, activation, rinsing, racking, current settings and post-plating inspection must be assessed together. See our guide to electroplating defects.
The advantage of robotic and manual lines
Having both robotic and manual lines at Serel Metal is a real advantage in preparation and plating. Robotic lines keep process times consistent on series and repeat work; manual lines give flexibility for special parts, sensitive surfaces and work that needs operator control.
This lets us choose the process according to the part’s shape, material and the finish required, instead of forcing the same approach on every part.
Conclusion
Surface preparation is the foundation of quality plating. Without correct cleaning, activation, rinsing and process control, a durable and even finish is hard to achieve. Our aim is not only a bright surface, but a finish that adheres, stays even and suits the way the part will be used.
Frequently asked questions
Why does plating peel off?
Most often because of oil, oxide or residue left on the surface before plating, or weak rinsing between tanks.
Should parts arrive polished?
Either works. Tell us whether parts will arrive polished or whether grinding and polishing should be included; see our plating RFQ checklist.
Get an initial assessment for your parts
Share the material, quantity and the finish you want; we will come back quickly with the right process.