Tag Archives: is bottom paint primer needed

How To Apply Bottom Paint To Bare Fiberglass

The following steps should be taken to insure good adhesion of bottom paint to a fiberglass or gelcoated hull.

Premium Blister Protection and Adhesion System ** Best Paint Option

  • Sand and Clean: Sand to a uniformly frosty, dull looking surface with 80-100 grit (no finer) sandpaper, rewash with S-80 Wax N’ Grease Killer or S-90 De-Wax Etch & Cleaner.
  • Apply Primer: Seal the surface with 2-3 coats of Tuff Stuff, or other high build epoxy primer. For Tuff Stuff, apply the first coat of primer and allow the surface to dry to become tacky. Temperature and humidity affect the dry time, but you will know when to apply your next coat of primer once the paint film becomes “tacky”. You should be able to firmly press your thumb into the paint film and leave a thumbprint without any primer coming off the surface. You should use this method in between coats of primer and your first coat of antifouling paint. When applying over multiple days, it is always best to go overnight between coats of primer instead going overnight between the final coat of primer and the first coat of bottom paint. Additional information can be found on the Tuff Stuff Technical Data Sheets.
  • Apply Bottom Paint: Apply minimum of two coats of Sea Hawk bottom paint. Allow 3 to 6 hours between coats and a minimum overnight dry. See the specific Technical Data Sheet for antifoulant being used. Some antifoulants may require more than 2 coats.

Sanding System** Better Paint Option

  • Sand and Clean: Sand to a uniformly frosty, dull looking surface with 80-100 grit (no finer) sandpaper, remove any residue.
  • Apply Bottom Paint: Apply minimum of two coats of bottom paint. Allow 3 to 6 hours between coats and a minimum overnight dry. See the specific Technical Data Sheet for antifoulant being used. Some antifoulants may require more than 2 coats.

Simple No Sand System ** Good Paint Option

  • Apply Primer: Apply one thin coating of 1266 Non-Sanding Primer. This coating is applied at a maximum of 1-2 mils WFT. Excessive buildup can cause a lack of adhesion. Minimum dry time is 20 minutes with a maximum of one hour.
  • Apply Antifoulant: Apply minimum of two coats of Sea Hawk antifouling paint. Apply first coat of antifouling within 2 hours of applying primer. Apply 2nd coat of antifouling allowing 3 to 6 hours between coats and a minimum overnight dry.

Note: Do NOT use a copper based paint on metal running gear and parts. You should use a metal free bottom paint such as Sea Hawk Outdrive Paint, priming it with Tuff Stuff first.

If the boat is taken down to gelcoat, is primer needed when applying bottom paint?

TUFFSTUFFnewPrimer for bottom paint is not necessary. However, if you use Tuff Stuff marine epoxy primer on the bare fiberglass, it will provide protection against blisters and any moisture. It will also improve adhesion to the hull. Tuff Stuff marine epoxy primer will last for many years. It cannot be applied over paint, it must be applied on gel coat (bare fiberglass).  It only needs to be applied once, while bottom paint should be applied every season or two depending on your conditions.

If you decide to use Tuff Stuff, here is the link. You should apply at least two coats.

See Related Article> Application of a Marine Epoxy Primer