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Interlux Bare Fiberglass Bottom Paint Guide


Painting bare fiberglass boats


BOAT HULL PREPARATION

1. Since the boat may never have been painted, take extra care and time in preparing the bottom before proceeding to the system of choice. Clean surface carefully, start by removing all contaminants and "Mold Release Wax" on the surface as follows.

2. Scrub the surface thoroughly using soap and water and a stiff brush. Flush with fresh water to remove soap residue. Allow surface to dry. Then proceed with either of the two following options:

Option 1: Apply Fiberglass Surface Prep YMA601 with a maroon, 3M, Scotch-Brite pad and scrub well. Flush with fresh water or wipe off with a clean, wet cloth ensuring that no traces of Fiberglass Surface Prep remain.

Option 2: Dampen cheesecloth with Interlux Fiberglass Solvent Wash 202. Wipe thoroughly to remove all surface contamination and cleaners. Wipe off with a clean, dry rag before liquid dries. Wipe only a few feet at a time.

3. Lightly spray the surface with water to insure all contamination has been removed. If water beads up or separates, wax is still present. Repeat until water no longer beads. At this point all mold release agents, wax and other contaminants should have been removed. Proceed to one of the following No Sand Method, Interprotect Method or Sanding Method.



BARE FIBERGLASS - SANDING SYSTEM

After the surface has been prepared as described above Sand entire surface well with 80-grit sandpaper until flat matte finish is obtained. Remember to change sandpaper frequently. Wipe off sanding residue with Fiberglass Solvent Wash 202. Apply two coats minimum of Interlux antifouling paint.

Whether the boat is new or a few years old "Mold Release Wax" and other contaminants like dirt, grime, dust, oils and even road salt can be present on the bottom of the boat. It is important to properly prepare the bottom of the boat before proceeding.




SYSTEM 1: NO SAND METHOD

Bottom painting bare fiberglass, Polyester or Vinylester gelcoats or epoxy resin

  1. Follow the Boat Hull Preparation instructions above.
  2. Using a 1/8 inch foam or 1/4 inch mohair solvent resistant roller, apply one thin continuous coat of Fiberglass No Sand Primer. Apply in one direction only without recoating.
  3. Only one coat of Fiberglass No Sand Primer is required. Antifouling overcoat times will vary due to wide variations in temperature and humidity. The only safe method to determine when the Interlux Fiberglass No Sand Primer is "Ready-to-Overcoat" is to check the paint film using the "Thumb Print" test. If the primer feels tacky and you can leave a thumb print in the paint film without getting any paint on your thumb, the Fiberglass No Sand Primer is "Ready-to-Overcoat". Test the paint film in the area you started applying the primer no later than 30 minutes after starting the application. Continue testing every 15 minutes using the "Thumb Print" test until reaching the "Ready-to- Overcoat" stage. Immediately, begin to apply the Interlux antifouling paint once the primer has reached the "Ready-to-Overcoat" stage.
Note: If you miss the overcoat time between the Fiberglass No Sand Primer and the antifouling paint you may apply another coat of primer for up to 72 hours of initial application.
   


Top Tip
  • One coat Fiberglass No Sand Primer applied at the recommended WFT; may not hide the gelcoat completely when applied properly.
  • Fiberglass No Sand Primer cannot be used with the following Interlux antifouling paints: VC17m® Extra, VC17m, VC Offshore, Baltoplate, Micron® 66™, Ultra™, Super KL or Micron Optima. Do not use with any water based or vinyl based antifouling paints.
  • Fiberglass No Sand Primer is moisture sensitive. Do not leave containers open during application. Once project is complete discard all remaining Fiberglass No Sand Primer.
  • Do not apply Fiberglass No Sand Primer if the relative humidity exceeds 85% or if temperature exceeds 95°F (35°C).



SYSTEM 2: LOW VOC NO SAND METHOD

Painting bare fiberglass, Polyester, Vinylester gelcoats or epoxy resin

  1. Follow the Boat Hull Preparation instructions on page 2.
  2. Apply one coat of Low VOC Fiberglass No Sand Primer YPA142.
  3. Apply two coats of Fiberglass Bottomkote® Aqua or Micron® Optima.

Should it rain during or immediately after application, the coating must be allowed to dry for a minimum of 24 hours before overcoating. If temperature is less than 50°F (10°C) allow a minimum of 48 hours prior to overcoat.

DRY TIMES FOR LOW VOC FIBERGLASS
NO SAND PRIMER YPA142
Temperature
(Ambient)
Overcoat
Time
Minimum
Overcoat
Time
Maximum
Launch
Time
Minimum
Launch
Time
Maximum
40°F (5°C)
50°F (10°C)
60°F (16°C)
73°F (23°C)
95°F (35°C)
8 hours
6 hours
4 hours
2 hours
2 hours
1 week
1 week
1 week
1 week
1 week
4 days
4 days
3 days
3 days
2 days
See launch
times of
Micron
Optima or
Fiberglass
Bottomkote
AQUA



SYSTEM 3:HIGH PERFORMANCE NO SAND METHOD

For new or non-blistered hulls

  1. Prepare the surface as per instructions on page 2 using the Interlux Fiberglass Surface Prep YMA601 with a maroon, 3M, Scotch-Brite padmaroon, 3M Scotch- Brite® pad.
  2. Apply 1 coat of InterProtect 2000E using a 3/8" solvent resistant nap roller. Appropriate coverage is 240 sqft/gal. To determine if the InterProtect 2000E is ready to overcoat, check the paint film using the "Thumb Print" test. If the InterProtect feels tacky and you can leave a thumb print in the paint film with out getting any paint on your thumb, it is "Ready-to-Overcoat". Test the paint film in the area you started applying the primer no later than 30 minutes after starting the application. Continue testing every 15 minutes using the "Thumb Print" test until reaching the "Ready-to-Overcoat" stage. Immediately, begin to apply the Interlux antifouling paint.
  3. Apply 2-3 coats of Interlux antifouling paint.

Top Tip

Up to 2 weeks may be left between coats of InterProtect 2000E but the time between the last coat of InterProtect 2000E/2001E and the first coat of antifouling are much shorter and temperature dependent. The "Thumb Print" test is the best method to use to determine when to overcoat the InterProtect 2000E with antifouling paint. If maximum dry times are exceeded, apply another coat of InterProtect® 2000E/2001E and then be sure to hit the proper overcoating interval before the application of the antifouling paint.

These overcoat times do not apply to performance or vinyl antifouling such as VC17m® Extra, VC17m®, VC® Offshore, Baltoplate and VC® Performance Epoxy.

To apply performance or vinyl antifoulings apply at least one extra coat of InterProtect&Ireg; 2000E/2001E and allow to dry 24 to 36 hours. Then sand with 80-grit sandpaper. Be careful to leave at least 10 mils dry film thickness of epoxy after sanding. Apply the performance or vinyl paint of choice.




SYSTEM 4: INTERPROTECT® BLISTER PREVENTION METHOD

For new or non-blistered hulls Use this system on new boats or used boats where all antifouling paint has been removed.

  1. Follow boat hull preparation procedures as per instructions on page 2.
  2. Sand the gelcoat thoroughly using 80-grit sandpaper.
  3. Remove the sanding residue by wiping with Fiberglass Solvent Wash 202.
  4. Apply 10 mils (4-5 coats) of InterProtect 2000E.
  5. Apply 2-3 coats of Interlux Antifouling Paint.
See chart on page 4 for amounts needed.

Top Tip
Remember prior to sanding the hull, thorough dewaxing is very important. Sanding heats any remaining wax on the surface, and then pushes it into the open pores in the gelcoat. This will keep any antifouling paint or primer you apply from adhering.





ASSOCIATED PRODUCTS
YPA200 No Sand Primer. YAV135KIT Watertite Epoxy filler.
216 Special Thinner - To clean previous painted areas.

  
YPA142 Low VOC No Sand Primer.6216 Paint Conditioner for Low VOC System.

2000E Blister prevention system.2316N Reducing solvent - For clean up.

YMA601 Fiberglass Surface Prep - Pigmented water based abrasive cleaner for bare fiberglass.

2333N Brushing Reducer - For thinning and clean up.
202 Fiberglass Solvent Wash - To clean bare fiberglass and remove mold release wax prior to application.INTERLUX® ANTIFOULING Check compatibility.



HOW MUCH PAINT DO I NEED?

Determining how much paint you will need is fairly simple. The estimated surface area in the chart below is based on the average boat size and type so actual square feet can vary. It is best to actually measure the wetted surface area of the hull. If it is difficult to do, a close approximation can be made by multiplying the length overall, times the beam, times 85% (LOA X Beam X .85 = wetted surface area). Then divide the wetted surface area by the square foot coverage per gallon, of the product you are using. The result is the number of gallons needed for 1 coat. See product cans for per square foot coverage per gallon.

Below is an estimate of the amounts needed.

BOAT SIZE & TYPE BOAT ESTIMATED SURFACE AREA FIBERGLASS NO SAND PRIMER 1 COAT INTERPROTECT 2000E/2001E 4-5 COATS ANTIFOULING PAINT 2 COATS
18' Power & Sail 120 Sq. Feet 120 Sq. Feet 120 Sq. Feet 0.5 gallons
21' Power & Sail 150 Sq. Feet 1.15 Quarts 2.5 gallons 0.75 gallons
28' Power & Sail 240 Sq. Feet 1.8 Quarts 4 gallons 1.25 gallons
31' Sailboat 270 Sq. Feet 2 Quarts 4.5 gallons 1.3 gallons
32' Sportfish 330 Sq. Feet 2.25 Quarts 5 gallons 1.5 gallons
36' Cruising Sailboat 350 Sq. Feet 2.5 Quarts 5.5 gallons 1.65 gallons
36' Powerboat 370 Sq. Feet 2.60 Quarts 5.75 gallons 1.75 gallons
41' Cruising 435 Sq. Feet 3.25 Quarts 7.25 gallons 2.2 gallons
42' Powerboat 500 Sq. Feet 3.75 Quarts 8.5 gallons 2.5 gallons
53' Cruising Sailboat 590 Sq. Feet 4.5 Quarts 10 gallons 3 gallons
53' Powerboat 650 Sq. Feet 4.85 Quarts 10.75 gallons 3.25 gallons




This pdf from Interlux offers more info on painting bare fiberglass boats


To learn more about interlux paint visit





BOAT PAINTING GUIDE
Bottom                          Antifouling
     Blister Repair & Prevention

Interlux Antifouling Basics
How Antifouling Paint Works
Interlux Antifoulant Selection Guide
Painting Bare Fiberglass Bottoms
Antifouling Paint Systems for Various Substrates
Handy Specifications
How To Paint Previously Painted Bottoms
Interlux Applying Antifouling Advice
Antifouling Paint Calculator
Antifoulant on Aluminum Hulls
Interlux Antifoulant on Metal Outdrives, Keels and Centerboards
Hints for the Perfect Bottom Finish
Interlux Antifoulant FAQ
 
What is Osmosis Gelcoat Blistering
How to Recognize and Treat Osmosis Gelcoat Blisters
Protect Against Gelcoat Blisters with Interlux Interprotect
Interlux Gelcoat Blister Repair FAQ
 
 



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