Paint an aluminium boat part above the waterline

Guided shopping manual

Guide to painting an aluminium boat part above the waterline

Aluminium boat parts above the waterline need clean metal, removed oxidation and the right primer stage before the visible finish, because smooth aluminium gives weak grip when it is not keyed properly.

What do you need to paint an aluminium boat part?

Cleaning and degreasing

Mipa silicone remover in liquid or spray format removes grease, silicone and wax before sanding, priming or coating.

Surface keying

MP Hand Block Soft or MP Sanding Sponge helps dull glossy areas and keep curved edges even before primer or topcoat.

Epoxy primer for mixed substrates

Mipa EP 100-20 is the epoxy primer method for steel, zinc-coated steel, aluminium, fibreglass and mineral substrates before the finishing coat.

Gloss polyurethane finish

Mipa PU 250-90 gives a glossy 2K polyurethane finish for above-water panels, with the matching hardener and 2K thinner used in the same coating stage.

Spray finish for small aluminium parts

Mipa Mix PU 250 2K Paint Spray 48+ is useful for smaller removable above-water aluminium parts when a prepared 2K spray finish is the practical method.

How to paint an aluminium boat part above the waterline

1
Clean the part

Remove salt, grease, polish and handling marks before sanding or scuffing the aluminium.
2
Remove oxidation

Abrade dull or powdery aluminium until the surface is sound and evenly keyed.
3
Prime the prepared metal

Use the epoxy primer method on exposed aluminium before the visible polyurethane coating.
4
Apply the topcoat

Use the gloss PU finish in light, even coats with the correct hardener and thinner for that stage.
5
Let the finish harden

Refit the part only after the coating has enough cure to resist marks around fasteners and edges.

Which aluminium coating products should you choose?

For bare aluminium

Choose EP 100-20 primer after cleaning and sanding so the finish has a stable foundation.

For removable fittings

Choose the spray method for smaller loose parts where controlled can application is easier than setting up liquid coating.

For larger surfaces

Choose the liquid PU topcoat system for better film control and a more even gloss finish.

Technical details

Mipa EP 100-20 is listed for aluminium as well as steel, zinced steel, fibreglass and mineral substrates.
The gloss topcoat stage uses Mipa PU 250-90 with its matching hardener and 2K thinner.
Oxidation, salt and hand grease should be removed before coating because aluminium contamination reduces adhesion.
This page is for aluminium parts above the waterline, not immersed hull surfaces.

Practical suggestion

Coat aluminium soon after preparation where practical, because freshly abraded aluminium can begin to oxidize again before the primer has been applied.