How to Prep The Surface of Different Materials for Hydro Dipping
Apr 15th 2026
Great dips start before your printed Hydokon film hits the water. If you want consistent adhesion and clean finishes, surface prep matters as much as your basecoat and activator. The right prep depends on the material, because plastics, metals, powder coat, and wood all behave differently.
This guide breaks down reliable surface prep steps by substrate, plus the most common failure points that lead to peeling, fisheyes, and “ghosting.”
The goal of surface prep
Surface prep is about two things:
- Clean: remove oils, silicones, waxes, polishing residue, mold release, and dust
- Key: create a uniform mechanical tooth for primer/basecoat to bite into
If either step is skipped, the dip can look perfect today and fail later.
Universal prep steps (works for most materials)
- Wash with soap and water first (removes grime that solvents can smear).
- Degrease with an appropriate surface cleaner. Use lint-free wipes and change them often.
- Scuff/sand to a uniform scratch pattern (no shiny spots).
- Blow off dust and wipe again before primer/basecoat.
- Use gloves after final clean to avoid reintroducing oils.
Now, tailor the “scuff” and “adhesion” steps to the material.
Plastics (ABS, polypropylene, nylon, polycarbonate)
Plastics are the most common source of adhesion issues because many contain mold release agents or have low surface energy.
Best practice process
- Wash thoroughly, especially textured areas and seams.
- Degrease with a plastic-safe cleaner (avoid aggressive solvents on sensitive plastics).
- Scuff evenly. For most parts, a fine abrasive pad or light sanding works well. The goal is a consistent dull finish.
- Adhesion promoter is often the difference-maker on low-energy plastics (especially polypropylene).
- Prime/basecoat per your paint system, then dip.
Common failures and fixes
- Peeling at edges: not enough scuffing or missed adhesion promoter.
- Fisheyes: silicone contamination from dressings or interior sprays. Reclean and isolate the work area.
- Soft basecoat: basecoat not cured enough before dipping. Follow your paint system timing.
Metals (aluminum, steel, stainless)
Metals usually bond well, but corrosion, oxidation, and machining oils can cause defects if not removed.
Best practice process
- Degrease to remove machining oil and fingerprints.
- Remove oxidation on aluminum or rust on steel before coating.
- Sand/scuff to a uniform tooth. For bare metals, consistent sanding helps adhesion.
- Use the right primer: for many paint systems, an epoxy or etching primer improves adhesion and corrosion resistance.
- Basecoat and dip once the coating system is ready.
Common failures and fixes
- Paint lifting: oil or oxidation left behind. Reclean, resand, and reprime.
- Rust bleed-through: inadequate primer or corrosion prep.
Powder coat
Powder coat can be an excellent base, but only if it is fully cured and properly keyed. A glossy, slick powder surface often needs abrasion to hold paint and the dipped layer reliably.
Best practice process
- Confirm cure: uncured or undercured powder can cause adhesion issues later.
- Degrease to remove handling oils and shop contaminants.
- Scuff thoroughly to remove gloss and create tooth. Avoid leaving shiny patches.
- Spot-check edges: powder edges can be slick and cause peeling if not keyed.
- Apply basecoat compatible with the powder system, then dip.
Common failures and fixes
- Dip peels like a sticker: powder was too glossy and not scuffed enough.
- Chipping at edges: missed scuffing on corners, or impact-prone edges need extra prep and clear.
Wood
Wood introduces a different challenge: porosity. If wood is not sealed properly, it can absorb moisture and solvents unevenly, causing bubbles, texture telegraphing, or a rough finish.
Best practice process
- Sand smooth and consistent. Remove mill glaze and sharp fibers.
- Remove dust completely (tack cloth or appropriate wipe for your system).
- Seal the wood so it is non-porous before dipping. Multiple light coats are often better than one heavy coat.
- Sand the sealer lightly to level the surface if needed.
- Basecoat and dip once fully cured per your coating system.
Common failures and fixes
- Bubbles or pinholes: trapped air releasing from porous wood. Seal better and allow full cure time.
- Grain telegraphing: not enough leveling coats or sanding between coats.
Quick reference: prep checklist by material
- Plastics: clean + scuff + often adhesion promoter
- Metals: degrease + remove oxidation + proper primer
- Powder coat: confirm cure + degrease + aggressive scuff (remove gloss)
- Wood: sand + seal to non-porous + level + basecoat
Common mistakes that cause failures
- Skipping soap-and-water wash and jumping straight to solvents
- Using one dirty rag to “clean” the whole part
- Leaving shiny areas that never got scuffed
- Touching parts with bare hands after final wipe
- Rushing primer/basecoat cure times
Final tip: prep is your insurance policy
If you want a professional finish that lasts, treat prep as the foundation. When the surface is clean, uniformly keyed, and properly coated for the material, hydrodipping becomes far more consistent and repeatable.
Want better consistency? Track the material, prep method, basecoat used, and cure time on each job. A simple log helps you spot patterns fast and eliminates guesswork.
If you have any questions about Hydrokon Water Transfer Film or how our printable film can be incorporated into your hydrodipping workflow, contact Hydrokon today.