Category Archives: Primer

Can you use water-based bottom paint over a marine epoxy primer?

Putting a water-based bottom paint  (WBP) over a solvent based primer can be done with some modified application procedures. You do NOT want to make the window, or hot coat the water based paint over the solvent based primer such as Tuff Stuff high build marine epoxy primer. If you do, it will mud crack. So instead of putting on the WBP over the Solvent Primer in the same day, you need to wait for the primer to totally cure. Then you have to sand it with 80 grit sandpaper before apply WBP. This is a lot of extra work and very difficult to sand = extremely hard surface. So the best thing to do when using a high build solvent based epoxy is to coat it with a solvent based paint. That way you skip the extra time and labor with sanding.

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

Application of Marine Epoxy Primer to a Boat

Marine Epoxy systems on the bottom of bare fiberglass is the best way to protect your boat against blisters. It also provides added adhesion of the bottom paint to the hull. Here are the steps that you need to take for proper application of a marine epoxy primer (barrier coat system) to the bottom of a boat.

Preparation

Clean
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.

Sea Hawk s-80 Wax N Grease KillerA. Clean and de-wax fiberglass hull with S-80 Wax N’ Grease Killer solvent based dewax. Saturate cheeseclothrag 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

Sea Hawk S-90 Low VOC De-Waxing Etch & CleanerB. 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 beadingon 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.

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 S-90 De-Wax Etch & Cleaner .

Apply Marine Epoxy Primer
TUFFSTUFFnewSeal the surface with 2-3 coats of Tuff Stuff Epoxy Primer. Apply the first coat of marine epoxy 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 marine epoxy 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 high build marine epoxy primer coming off the surface. You should use this method in between coats of marine epoxy primer and your first coat of bottom paint.

Tip: When applying marine epoxy primer over multiple days, it is always best to go overnight between coats of marine epoxy primer instead going overnight between the final coat of marine epoxy primer and the first coat of bottom paint. When over coating Tuff Stuff Epoxy Primer it is important to meet the required over coating times in order to achieve the best adhesion because temperature and humidity control dry times. It is hard to give exact times of cure. An easier rule in epoxies is when the coating is dry to the touch, yet still has some tack, it is ready to be over coated. However, if the coating is completely cured (after 24 hours) it needs to be thoroughly sanded with 80 grit sand paper to remove shine. If the marine epoxy primer is not sanded after full cure, bottom paint will not adhere.

Apply Bottom Paint to Marine Epoxy Primer
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 bottom paint being used. Some bottom paint may require more than 2 coats.