FGCI High Performance Isophthalic Putty

Isophthalic Putty Filler Kit


If you plan on using our Isophthalic Resin, you want to make sure you are using the same quality of putty and filler. This works seamlessly with our other isophthalic products to produce a consistent final product.

Includes MEKP catalyst!

*For Drum Quantities – please contact us via our Contact Us page. 


Water Resistant Isophthalic Putty

Our Isophthalic Putty has exceptional water resistance, which makes this product fantastic to use below the water line on boats and within tank making applications! Effortlessly bonds between substrates and lamination layers.

Isophthalic Putty Benefits:

  1. Extremely high water resistance
  2. Easily sanding for a smooth finished surface
  3. Great for below the waterline on boats
  4. Exactly what you want for tank building
  5. Requires MEK 925 (not included)
Catalyst Concentration Chart - Resins and Gelcoat

Materials Needed
Mix & Measure Buckets
Personal Protective Equipment (PPE)
Measuring Cups
Mixing Sticks/Power Mixer

Step 1:
Mix equal parts Base and Activator (1:1 by volume) or mix by weight (approx. 112 parts A-Side Base to approx. 100 parts B-Side Activator).

Step 2:
Mixing and metering equipment must accommodate the 1:1 by volume mix ratio.

Step 3:
Mix thoroughly using a stir stick or a mechanical mixer. Please refer to Typical Reaction Profiles of Liquid Foam Chart for mix times.

Step 4: Pour immediately after mixing.

Step 5: Allow cooling between pouring.

Directions may vary by application. For technical support and assistance with critical applications or large pours, please feel free to contact Customer Service at 1-888-849-0588.

Cleaning Polyester Resin:

Use Acetone to clean brushes and rollers. A small bucket of solvent can be used to clean tools.

PLEASE NOTE: This information is provided in good faith and correct to the best of our knowledge. No warranty, guarantee, or representation is made as to the sufficiency of the information for the safe use of the product, nor to relieve the end user of any Federal, State, or Local regulatory responsibility.


  1. Charlie Norris

    “I love fiberglass coatings. They have great products and excellent advice. I'm trying to open a boat repair shop in St . Mary's, GA and my supply WILL come from fiberglass coatings. When I lived in the Fl. Keys for 36 years and worked for a towing and salvage Co for 15 years all our supplies came from Fiberglass coatings. Great service and never were disappointed. Keep up the great job everyone.”
  2. Brian Lewis

    “The staff are very knowledgeable and friendly Have always gotten the right stuff for the right job. Pat,mark,Colby,Ryan your the best. Pat is the walking encyclopedia of FGCI.”
  3. Justin Lammers

    “Been working on a skiff project and using all FGCI products. They came highly recommended by my friends who are boat builders. It is the highest quality resins, glass, and gelcoat for the money. They made it really easy for a newer person to boat building. The customer service is phenomenal and they are always knowledgeable and ready to help with any questions I had.”