Coating performance depends on applying the correct dry film thickness—too thin and you don't get the protection specified, too thick and you risk cracking, extended cure times, or wasted material. Understanding how to measure and control film thickness ensures INSECO coatings perform as designed.
Why Film Thickness Matters
INSECO coatings are formulated to deliver specific performance characteristics at defined film thicknesses. A coating designed for 3-4 mils dry film thickness won't provide adequate protection at 2 mils, regardless of how well you prepared the surface. Conversely, applying 8 mils when 4 is specified wastes material, extends cure time, and may cause issues like cracking or poor intercoat adhesion.
Each product's technical data sheet specifies recommended wet and dry film thickness. Wet film thickness is what you measure during application, while dry film thickness is what remains after solvents evaporate. The ratio between them depends on the coating's percent solids—higher solids products retain more material after drying.
Using Wet Film Thickness Gauges
Wet film thickness gauges are inexpensive tools that provide immediate feedback during application. The most common type features notches of varying depths—you press the gauge into freshly applied coating, then read which notch shows coating contact. This tells you the approximate wet film thickness, which you can compare against target specifications.
Check wet film thickness regularly throughout application, not just once at the start. Variables like roller loading, spray gun settings, surface texture, and applicator technique all affect film build. Taking measurements every few minutes lets you adjust technique to maintain proper thickness before you've coated large areas incorrectly.
Calculating Target Wet Film Thickness
To determine target wet film thickness, divide the desired dry film thickness by the coating's percent volume solids (as a decimal). For example, if you need 4 mils dry and your INSECO product has 50% volume solids, you need to apply 8 mils wet (4 ÷ 0.50 = 8). Products with higher solids require less wet film to achieve the same dry thickness.
This calculation is critical when switching between products or application methods. A high-solids coating might require only 5 mils wet to achieve adequate dry film, while a lower-solids product might need 10 mils wet for the same protection. Always check the technical data sheet for the specific product you're using.
Adjusting Application Technique for Proper Build
If measurements show you're applying too thin, slow your application speed, use a longer roller nap, adjust spray gun settings for heavier deposit, or apply additional coats. If you're applying too thick, work faster, use shorter nap rollers, adjust spray techniques, or thin the coating according to technical data sheet limits.
Surface texture dramatically affects film thickness. Rough substrates consume more coating to fill profile peaks, requiring heavier application than smooth surfaces. Very rough concrete or aggressive blast profiles might need 50% more coating than calculations suggest to achieve adequate coverage over the entire profile.
Verifying Dry Film Thickness After Cure
After coating cures, verify dry film thickness using a dry film thickness gauge appropriate for your substrate. Magnetic gauges work on steel, while ultrasonic gauges measure thickness on non-ferrous metals, wood, or concrete. Take multiple readings across the coated area since thickness often varies, and compare results against specifications.
If dry film thickness falls short of requirements, you'll need to apply additional coats. This is why measuring wet film during application matters—catching thin application early prevents having to add coats later. Document your thickness measurements, particularly for commercial or industrial projects where specifications require verification of proper film build.
Common Thickness Problems and Solutions
Edges and corners typically receive less coating than flat surfaces due to surface tension. These areas often need extra attention or stripe coats to achieve adequate protection. Inside corners trap excess material, potentially creating thick spots that dry slowly. Adjust technique to address these predictable variations rather than hoping for uniform thickness everywhere.
Porous substrates require seal coats that penetrate deeply before building topcoat thickness. Trying to achieve full film thickness in one coat on porous concrete or wood often results in inadequate penetration. Apply a thin first coat that soaks in, then build thickness with subsequent coats on the sealed surface for better results.
Blog 2: Understanding Pot Life and Working Time with INSECO Multi-Component Products
Multi-component INSECO coatings deliver superior performance through chemical reaction between components, but this same reaction creates time limits on how long mixed material remains usable. Understanding pot life and working time prevents waste and ensures successful application.
What Pot Life Actually Means
Pot life is the time after mixing that coating remains at low enough viscosity for proper application. As chemical reaction progresses, mixed coating thickens, eventually becoming too viscous to spray, roll, or brush effectively. The technical data sheet specifies pot life under standard conditions—typically 77°F (25°C)—but actual pot life varies significantly with temperature.
Don't confuse pot life with cure time. A coating might have a 30-minute pot life but take 24 hours to cure fully. Pot life simply indicates when the material becomes too thick to work with, not when it's done curing. Using coating beyond its pot life results in poor application characteristics, difficulty achieving proper film thickness, and potentially compromised performance.
Temperature's Impact on Pot Life
Temperature dramatically affects chemical reaction speed. As a general rule, every 18°F (10°C) increase in temperature approximately halves pot life, while cooler temperatures extend it. INSECO epoxy with a 30-minute pot life at 77°F might thicken in just 15 minutes at 95°F, or remain workable for an hour at 60°F.
Substrate temperature matters as much as air temperature. Applying coating to surfaces baking in direct sunlight can trigger rapid reaction even if ambient air temperature seems reasonable. Plan application timing to avoid extreme substrate temperatures when possible, or adjust batch sizes to account for shortened pot life in hot conditions.
Mixing Only What You Can Use
Calculate realistic application rates before mixing material. If you can apply 10 square feet per minute and your pot life is 30 minutes, don't mix enough material for 500 square feet. Account for the time spent actually coating versus setup, moving equipment, and other non-application activities. Beginning applicators especially should mix conservative batches until they develop accurate sense of their application speed.
For large areas, set up a system where one person mixes batches while another applies, timing new batches to be ready as previous ones near the end of their pot life. This assembly-line approach maintains continuous application without rushed work or wasted material from exceeding pot life.
Recognizing When Material Has Exceeded Pot Life
Viscosity increase is the primary indicator that coating is approaching or past its pot life. Material becomes noticeably thicker, harder to roll or spray, and doesn't flow or level properly. Don't try to extend pot life by thinning—adding solvent to material that's already reacting doesn't restore proper working characteristics and may compromise performance.
Heat generation often accompanies reaction in multi-component products. If your mixed container feels warm or hot to the touch, reaction is progressing rapidly. This is especially common with large mixed batches where the mass of material generates and holds heat, accelerating reaction. Using shallow containers rather than deep buckets can reduce this self-heating effect.
Extending Effective Working Time
While you can't extend pot life beyond the chemistry allows, you can maximize effective working time. Keep mixed material in shade and away from heat sources. Pour material into roller pans or spray pots in smaller quantities rather than keeping large volumes in one container where heat builds up. Some applicators place mixed containers in ice baths during hot weather to slow reaction, though this requires careful monitoring to avoid condensation issues.
Work efficiently but don't rush so much that quality suffers. Proper technique and attention to coverage matter more than speed. If pot life constraints create constant pressure and rush, mix smaller batches more frequently. The few extra minutes spent mixing additional batches is usually worthwhile compared to fighting thickening material or wasting partially-used batches.
Cleanup Before Material Sets
Multi-component products become progressively harder to clean as reaction proceeds. Clean application equipment while coating is still within pot life—waiting until material has thickened makes cleanup significantly harder. Keep appropriate cleaning solvents on hand and use them generously. Dried two-component coatings often can't be removed without aggressive mechanical means that may damage equipment.
Don't pour unused mixed material back into original containers—this contaminates fresh material. Small amounts of leftover mixed coating should be disposed of according to local regulations. Factor expected waste into material calculations rather than trying to mix exactly the amount needed with no excess, which often leads to running short before completing the work.
Planning Application Around Pot Life Limitations
For projects requiring continuous wet edges to avoid lap marks, pot life constraints may dictate crew size and organization. Multiple applicators working in coordinated sequence can maintain wet edges across larger areas than a single person could cover within one batch's pot life. Plan these logistics before starting rather than discovering mid-project that you need more hands to work within pot life limits.
Consider whether pot life restrictions make a particular product appropriate for your project conditions and crew capabilities. Sometimes products with longer pot life or single-component alternatives better suit the specific application situation, even if they offer slightly different performance characteristics. The best coating is one you can apply correctly, not necessarily the one with ultimate performance specifications.
