Preparation

PREVIOUSLY PAINTED SURFACES WITH ANTIFOULINGS: Completely remove all old antifouling paint. For fiberglass - use Interlux Interstrip 299E, or sand or media blast. For steel or aluminium - sand, media blast or grind to near white metal following preparation instructions for metal below.
PREVIOUSLY PAINTED SURFACES WITH TWO-PART EPOXY PRIMER: Remove all contamination with Fiberglass Solvent Wash 202 or Fiberglass Surface Prep YMA601V. Follow directions on the product label. Fill any surface imperfections with Interlux Watertite or Interfill 830 following the product label instructions. After the surface has been properly prepared, sand the two-part epoxy primer with 80 grit sandpaper.The two-part primer does not need to be removed, it only needs to be sanded to add a mechanical etch for InterProtect HS to adhere to. Remove the sanding
residue by wiping with Interlux Fiberglass Solvent Wash using the two-rag method.
BARE FIBERGLASS: It is very important that bare fiberglass be properly prepared to prevent delamination of InterProtect. Remove mold release wax using one of the following Interlux products, Fiberglass Surface Prep YMA601V or Fiberglass Solvent Wash 202 following the product label instructions. Fill any surface imperfections with Interlux Watertite or Interfill 830 following the product label instructions. After the surface has been properly prepared, sand the fiberglass with 80 grit sandpaper. Remove sanding residue with Fiberglass Solvent Wash 202.
FIBERGLASS WITH BLISTERS: Completely remove all old antifouling paint with Interlux Interstrip 299E, sanding or media blast. Sand with 80 grade (grit) paper. Remove the sanding residue by wiping with Interlux Fiberglass Solvent Wash using the two-rag method. Open all blisters and remove any bad gelcoat and laminate. Open all blistered areas either by physical grinding or by sandblasting or peeling. On severely blistered boats the entire gelcoat below the waterline may need to be removed. Complete removal of the gelcoat should be done only after the advice of a competent Marine Surveyor. If the gelcoat has been peeled off, lightly sandblast or sand with 60-80 grit sandpaper to remove any soft
spots in the laminate, and to provide more surface area to aid in drying the hull. Wash the entire underwater surface with fresh water (preferably hot water) in order to remove glycol and other water-soluble contaminants. Repeat periodically during the initial phase of the drying process. Allow the hull to dry as long as is necessary (2-3 months average) to ensure all water has left the hull. Moisture in the hull will cause additional blistering. Accurately measure Epiglass Epoxy Resin and Hardener, mix well. Pour immediately into a wide flat tray to prevent premature curing. Mix only as much as you can use in 20 minutes. Apply Epoxy Resin to all areas where the gelcoat has been removed. Wait for a
minimum of four hours and scrub with a stiff bristle brush, using soap and water, to remove amine blush. Rinse with fresh water. Sand with 80 grade (grit) paper and remove sanding residue with Fiberglass Solvent Wash 202. If it has not been overcoated within 24 hours, rewash with fresh water. Fill any surface imperfections with Interlux Watertite or Interfill 830 following the product label instructions. Sand entire surface thoroughly with 80 grade (grit) paper. Remove sanding residue. Wipe the surface using Interlux Fiberglass Solvent Wash before beginning application of InterProtect HS.
BARE STEEL/LEAD: It is imperative to remove all grease, oil, dirt or other foreign contaminants by wiping down the surface with Interlux Fiberglass Solvent Wash 202 using the ‘Two-Rag' method. Grit blast or disc grind surface to a Sa 2.5 clean surface profile. For grit blast use medium mesh silica sand or other nonmetallic blast media, for disc grind use a 24-36 grit abrasive disc. Remove all blasting or grinding residue by brushing the surface with a stiff brush along with using clean (oil and water free) compressed air. Alternatively the surface can be vacuumed.
BARE ALUMINUM: It is imperative to remove all grease, oil, dirt or other foreign contaminants by wiping down the surface with Interlux Fiberglass Solvent Wash 202 using the ‘Two-Rag' method. Sand the aluminum with 40-60 grit sandpaper to a uniform 2-3 mils (50-75 microns) clean surface profile. After sanding remove all residue by using a clean (oil and water contamination-free) air line and by sweeping with a clean brush or broom.

Method:

Fiberglass blister prevention or repair - Apply enough InterProtect HS to reach Wet film Thickness (WFT) of 10 mils, Dry Film Thickness (DFT) of 7 mils.
For application to metals for corrosion protection - Within one hour of grit blasting, disc grinding or sanding, (make sure during the hour the surface stays clean and dry with no condensation or dew) apply the first coat of InterProtect HS directly to the bare metal. To protect against metal corrosion a 7 mil DFT barrier of InterProtect HS is required.
Apply enough InterProtect HS to reach Wet Film Thickness (WFT) of 10 mils, Dry Film Thickness (DFT) of 7 mils for below water, or a DFT of 5 mils and WFT of 8 mils for above water areas. This may take 3 coats by brush/roller, depending on the type of roller used, and 1 coat by spray, but the amount of paint is more important than the number of coats. When using InterProtect HS above the waterline with a topside finish, InterProtect HS needs to be overcoated by 1-2 coats of Epoxy Primekote. See Epoxy Primekote product datasheet for details.
Ultimate No Sand System: InterProtect HS provides a hard, durable coating with long lasting adhesive performance and eliminates the need for sanding before applying Interlux antifoulings. Once the surface has been prepared following the preparation instructions for bare fiberglass, apply one coat of InterProtect HS following the application instructions above. 

Hints:

Mixing: Ensure the correct volume mix ratio is used. Mix only as much as you can use in the stated pot life.
Thinner: Y2333N, Y2316N
Cleaner: Y202/Y2333N/Y2316N
Thinning: 10% maximum by volume
Airless Spray Tip size: 0.621 mm Pressure: 3000 psi.
Not suitable for application by pressure pot - Contact Interlux Technical Service for more information.
Brush Solvent resistant standard brush Roller Solvent resistant 1/4" or 3/8" nap rollers. A 1/4" roller will give a smoother finish however more coats may be necessary. A 3/8" roller will give a more stippled finish, texture may be visible and it may require fewer coats. Overall, a total of 10 mils WFT is required for an underwater barrier system.
Compatibility/Substrates: There are 2 separate overcoating intervals to be followed for all the antifoulings in the range, as well as above waterline use. Please refer to the overcoating chart for details. Product cannot be overcoated at thumb print tacky interval. InterProtect HS can not be used under VC17m Extra.

Number of Coats:

Barrier protection below waterline - As required to reach 10 mils WFT
Barrier protection above waterline - As required to reach 8 mils WFT
Ultimate No Sand System - 1 by spray, 1 by brush/roller
Coverage Barrier protection below waterline - 151 ft²/gal yields 7 mils DFT at 10 mils WFT
Barrier protection above waterline - 211 ft²/gal yields 5 mils DFT at 8 mils WFT
Ultimate No Sand System - 447 ft²/gal yields 2.4 mils DFT at 3.6 mils WFT

Application Methods: Airless Spray, Brush, Roller

Color: YPA420-Gray
Finish: Satin
Specific Gravity: 1.22
Volume Solids: 66%
Mix Ratio: 2:1 by volume (as supplied)
Converter/Curing Agent: YPA422
Typical Shelf Life: 2 yrs
VOC (As Supplied): 289 g/lt
Unit Size 1 US Gallon Kit

Interlux InterProtect HS Primer Product Data Sheet