Fiberglass Supply - Carbon Fiber and Composite Supplies for the 21st Century


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Gel Coat Calculators

Below are two gelcoat estimators for calculating the amount of gelcoat you will need.  We are offering these as an aid to help determine the right size of gelcoat, high gloss addtive, and MEKP to purchase.  Please keep in mind that these do not include wastage.  Wastage will vary based on a number of factors, for example when we spray a single small mold (8 sq. ft) it takes almost the whole quart of gelcoat due to the amount of gelcoat that is stuck to the sides of the spray cup.  When we spray multiple molds we get better coverage because we are dividing the waste from one cup (we refill it) across multiple molds.  It can also vary depending on the equipment you are using, pressure pots have much more waste than the G-100 dump gun. 

For top coat applications, i.e. repair, or finish coating, we strongly recommend using Duratec High Gloss Additive to thin the gelcoat and allow it to flow and cure like a paint.  There is a calculator below for determining how much you’ll need.

To use the calculator enter the square feet that you need to cover, then click the update button to get the quantities you’ll need.  The calculator does not automatically update after you change the square footage, you must click the update button.

To use the Top Coat calculator you must also enter your film thickness. The Gelcoat Estimator already has the thickness built in (aprox. 0.023”)

Gelcoat Calculator

Gelcoat Estimator Provided by Fiberglass Supply    
Square Feet To Cover  
Gelcoat Needed in Gallons  
MEKP Needed in Ounces  
Top Coat Gelcoat Application with Duratec High Gloss Additive    
Square Ft.  
Thickness in decimal inches (standard is 0.010 - 0.020 per coat)  
Duratec High Gloss in Gallons  
Gelcoat in Gallons  
MEKP in Ounces  
Notes: Multiple coats may be required to obtain opacity, hide varies by color
Duratec High Gloss is mixed with Gelcoat at a 1:1 ratio    
MEKP volume based on 2% initiator level, actual level will vary with shop conditions
Figures do not include wastage    
Use at you own risk    

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Fiberglass Supply 
 11824 Water Tank Rd. Burlington
 Washington, 98233 USA
Phone; (509) 493-3464