Monthly Archives: February 2011

What Is Bottom Paint?

What is bottom paint

What is Bottom Paint?

If you don’t know what bottom paint is, you are not alone. A boater that keeps his/her boat in the water for an extended period of time, must have bottom paint on the bottom of the hull to prevent growth (fouling) from occurring.

Bottom Paint also called antifouling paint, boat bottom paint, and anti-foul paint, is a special marine paint that is formulated with pesticides to keep those marine critters from growing on the bottom of the hull. Copper is most common pesticide used in bottom paints, and will prevent hard growth. Hard growth is considered mussels, barnacles, or any other crustacean that can attach to the bottom of the boat. Hard growth mostly occurs in warmer water and salt water. However, depending on your geographical location, hard growth will occur in fresh water and nutrient rich cool waters as well.

Some boat bottom paint is  also combine other pesticides (biocides) with copper to prevent soft growth. Soft growth refers to algae and grass.

Why do you need bottom paint? If you are going to keep your boat in the water for more than a couple of days, you will need some bottom paint!

Related Articles:

What is the difference between Hard Bottom Paint and Ablative Bottom Paint?

What Bottom Paint Can go Over Polyethylene?

Yes, you can apply bottom paint over polyethlene (plastic). We recommend applying an ablative bottom paint, preferably ablative such as Cukote.

bottom paint primerYou should sand the boat with a 60 grit sandpaper, then wash it off with S-80 Cleaner and Dewaxer. After it is cleaned, you should apply 1-2 coats of 1277 bottom paint primer. Let it dry overnight and then apply the Sea Hawk antifouling paint of your choice.

Do I Need a Reducer For Bottom Paint?

Reducers help the paint to dry faster or slower, depending upon the reducer you use. There is a warm weather reducer that makes it dry slower, and a cool weather reducer that make it dry faster.

Generally speaking, reducers should only be used in extreme weather conditions, or to thin the paint for a spray application.

Here is the link to reducers for bottom paint.

How to Apply Bottom Paint Over Existing Bottom Paint

Bottom Painting is not very technical, but you must have a clean surface to insure good adhesion.

Refer to the Sea Hawk Compatibility Chart to determine if your existing coating is compatible with Sea Hawk antifoulant paint choice.To insure that your bottom paint adheres to your existing coating, it is important to have a clean prepared surface and an existing coating that is in good condition.

Known Compatibility of Existing Bottom Paint:
Power wash (pressure wash) to remove any loose paint,dirt, grease, or any other surface contaminants.
Scuff sand with 80 grit sandpaper, or scuff with a 3M Scotch-Brite® 7447 pad scrubbing thoroughly. Remove all residue and let dry.
Apply minimum of two coats of antifoulant. 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.

Unknown Compatibility* of Existing Antifoulant:
Power wash (pressure wash) to remove any loose paint,dirt, grease, or any other surface contaminants.
Scuff sand with 80 grit sandpaper, or scuff with a 3M Scotch-Brite® 7447 pad scrubbing thoroughly. Remove all residue and let dry.
Apply 1 coat of Bottom Paint PrimersHAWKocon or 1283 Island Primer (see respective technical data sheet)
Apply minimum of two coats of antifoulant. 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.

Poor Condition of Existing Antifoulant:
If previous coating is cracking, flaking or peeling then strip antifoulant with Marine Paint Stripper, or by sanding or commercial blast. Refer to Bare Fiberglass Application Guidelines for new antifoulant application.

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.