Gelcoat to Catalyst Ratio Calculator
Calculate exact catalyst (MEKP) amount needed for gelcoat mixing. Essential tool for fiberglass workers, boat builders, and auto body professionals.
Mixing Parameters
Amount of gelcoat to be catalyzed
Catalyst percentage by weight
Mixing Results
Enter gelcoat parameters and click "Calculate Catalyst Amount" to see results
Safety Warning
Always wear appropriate PPE when working with gelcoat and catalysts. Work in well-ventilated areas and follow manufacturer safety guidelines. Incorrect mixing can cause health hazards.
Gelcoat to Catalyst Ratio Made Simple
When working with gelcoat, getting the catalyst ratio right is critical. Too little catalyst causes slow or incomplete curing. Too much can lead to cracking, discoloration, or unsafe heat buildup. The Gelcoat to Catalyst Ratio Calculator removes guesswork and helps you mix with confidence.
Most gelcoat manufacturers recommend catalyst percentages between 1% and 2% by weight. This calculator helps you determine the exact amount needed for any quantity of gelcoat, ensuring consistent and safe results.
Whether you're repairing a small ding on a boat hull or coating an entire automotive mold, precise catalyst measurement is the difference between a professional finish and costly rework.
Formula Used in the Calculator
Catalyst Calculation Formula
Catalyst Amount = Gelcoat Amount × (Catalyst Percentage ÷ 100)
Where:
- Gelcoat Amount = Weight of gelcoat to be catalyzed
- Catalyst Percentage = Percentage by weight (typically 1-2%)
- Catalyst Amount = Amount of MEKP or catalyst needed
The formula applies consistently across all supported units and automatically accounts for unit conversions.
Unit Support
The calculator supports four common weight units used in gelcoat mixing:
Metric Units
- Grams (g): Small batch mixing
- Kilograms (kg): Production quantities
Imperial Units
- Ounces (oz): Small repairs
- Pounds (lb): Larger applications
The calculator maintains consistency between input and output units, making it easy to work in your preferred measurement system.
Example Calculation
Boat Hull Repair Example
| Parameter | Value |
|---|---|
| Gelcoat Amount | 1000 grams |
| Catalyst Percentage | 1.5% |
| Formula Applied | 1000 × (1.5 ÷ 100) |
| Catalyst Required | 15 grams |
Mixing Instructions
Add 15 grams of MEKP catalyst to 1000 grams of gelcoat. Mix thoroughly but gently to avoid introducing air bubbles. The mixture will begin curing within 10-15 minutes at room temperature.
Choosing the Right Percentage
Longer Working Time
Best for beginners, large batches, or when you need more time to work. Slower curing but more forgiving.
Balanced Performance
Recommended for most applications. Good working time with reliable curing results.
Faster Curing
Use in colder conditions or when you need quicker setup. Shorter working time.
Note: Always follow manufacturer recommendations for specific gelcoat products. Environmental conditions may require percentage adjustments.
Final Thoughts
Accurate gelcoat mixing is not optional—it determines finish quality, durability, and safety. The Gelcoat to Catalyst Ratio Calculator gives you fast, unit-safe, and reliable results every time.
Whether you're repairing a small surface ding or coating a full mold, this tool ensures your catalyst measurement is always right. Remember to work safely, follow manufacturer guidelines, and test small batches first when working with new materials.