Category Archives: Primer

What Is Zinc Chromate Used For?

Zinc chromate is used for a wide range of applications. It is an odorless chemical compound primarily used as an industrial paint coating. The compound is a beneficial coating because it is an anti-corrosive and an anti-rust primer. It is primarily used to coat aluminum and iron materials. Developed by the Ford Motor company during the 1920’s, it was historically used on aircraft by the US military during the 1930’s and 1940’s. It is also widely used as a paint coating for the aerospace and automotive industries, as well as, a coating for boats, due to its ability to destroy organic growth on the surface and to protect aluminum from corrosion.

Zinc chromate is on the hazardous substance list and regulated by OSHA because studies have shown that not only is zinc chromate highly toxic, but it is also a carcinogen. It has been cited by ACGIH, NIOSH, DEP, IARC, HHAG and EPA.

What is zinc chromate used for

Duralux ZinKromate is a high-quality synthetic primer for use in light to moderate marine exposures. It is lead and chromate free so it is safe to use; however, it offers all of the performance and quality characteristics of zinc chromate without the health and application hazards. It has good chemical and corrosion resistance, dries fast, and allows single finish coat coverage when using a like-colored topcoat. ZinKromate performance primer adheres very well to steel, iron, aluminum, or partially rusted galvanized surfaces.

S-76 Strontium Chromate Tack Coat Primer is for use on properly prepared steel, aluminum or galvanized steel. S-76 is an anti-corrosive strontium chromate based primer that is specifically designed for underwater metal surfaces including hulls, running gear, and the lower units of outboards and I/O’s. It provides an excellent barrier to reduce pitting of the metal from galvanic corrosion.

S-76 Strontium Chromate Tack Coat Primer

Stromate Chromate tack coat primer may be used on bare aluminum in conjunction with Tuff Stuff High Build Epoxy to form a barrier for application of copper-based antifoulants.

If you have any questions about ZinKromate primer or Stromate Chromate tack coat primer, please call our technical expert team at 888-505-2313 Monday to Friday 8am-5:00pm EST.

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

Epoxy paint is a latex acrylic substance that may have a small amount of epoxy in the mix and provide a tough, durable protective coating that’s effortless to maintain. 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.

Tuff Stuff Marine Epoxy Primer

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

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.