Marine Paints, Marine parts and House paints at trade prices direct to public – Servicing the marine industry since 1914

Cement

Ferrocement

Ferrocement is a specialised form of reinforced concrete in which a matrix of steel rods and fine mesh is covered in a high quality mortar to produce a material of good tensile strength and flexibility. It is a relatively inexpensive boat building material with the added advantages of being fire resistant, extremely durable and easy to repair. However, it is relatively heavy material and a high degree of skill is required from plasterers and painters to produce a finish comparable with other boat building materials. It is recommended to use a two pack painting system on ferrocement.

Particular tips when painting ferrocement:

  • ensure new ferrocement is fully cured.
  • stone down the ferrocement using either a hand held medium grit arborundum stone lubricated with fresh water, or 120 grade wet or dry abrasive paper used wet.
  • alternatively, wet or dry abrasive blast the hull to obtain a slightly roughened and firm surface which is free of scum layer and contamination.
  • any wires or tie ends exposed during this process should be punched below the surface and filled
  • acid wash the surface using a recommended method, ie, approximately 5% w/w nitric or phosphoric acid solution. Leave the acid on the surface for 3 to 4 minutes to allow it to react with the compounds within the structure, then hose down with fresh water.
  • check that the surface has a pH reading of between 6.5 and 8.0 and that when scraped with a sharp knif, only a clean scratch is left
  • allow the surface to dry naturally

For advice on repainting ferrocement see the section on Repainting.

Ferrocement

Product no of coats recoating interval @ 10oC recoating interval @ 20oC coverage m2/lt thickness per coat wft tickness per coat dft thinner
ABOVE THE WATERLINE
Light Primer thinned 20% with 845 1 8h-60d 4h-30d 12 80 35 845
Light Primer thinned 5% 5 8h-60d 4h-30d 8 120 60 845
Poly Best onto Light Primer 8h-6d 4h-30d
Poly Best 2 36h-10d 16h-5d 15 75 35 851 spray
871 brush
BELOW THE WATERLINE
Light Primer thinned 20% with 845 1 8h-60d 4h-30d 12 80 35 845
Light Primer 5 8h-60d 4h-30d 9 120 60 845
tie coat – Underwater Primer onto Light Primer 1 2h-4d 1h-2d 10 100 40 823
Hempel Antifouling onto Underwater Primer 2 6h- indefinite 3h-indefinite 13 75 40 808