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.

Preparation

  • Clean Surface: When painting a bare fiberglass / gel coat hull for the first time, it is extremely important that all contaminants such as grease, oil, wax, salt, or other foreign material are completed removed prior to sanding or application of a Sea Hawk System. Scrub the surface with a detergent soap and stiff bristle brush.
  • Dewax Surface:  Clean and de-wax fiberglass hull with S-80 Wax N’ Grease Killer solvent based dewax. Saturate cheesecloth rag and wipe thoroughly to remove any cleaner and contaminants. Be sure to remove any residue before it dries and change rags frequently to insure contaminants are completely removed.

OR

  • Apply S-90 De-Wax Etch & Cleaner with a maroon 3M Scotch-Brite® pad scrubbing thoroughly. Do not allow cleaner to dry on the surface and remove by flushing with water.Rinse entire surface with water and check for any beading on the surface which will indicate that wax is still present.If necessary repeat step 2 again until the surface is contaminant-free. Choose your system below.

Premium Blister Protection and Adhesion System

  • 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

  • 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.

No Sand System with Superior Blister Protection

  • Apply Primer: Apply a one step primer, such as Bottom Paint Primer, by Seahawk. Review Technical Data Sheet to compare the primers and best one for the paint you choose.
  • Apply 2nd Primer: Seal the surface with 2-3 coats of Tuff Stuff, or S-78 High Build Primer. 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 antifouling. Additional information can be found on the Tuff Stuff, S-78 Technical Data Sheets.
  • Apply Antifoulant: Apply minimum of two coats Sea Hawk Premium antifoulant not allowing more than 24 hours since the last coat of Tuff Stuff / S-78 High Build Epoxy Primer.

Simple No Sand System

  • 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