Temperature, humidity, and weather conditions can make or break a uPVC spraying job. The right conditions help ensure perfect adhesion, consistent gloss, and long-term durability, while the wrong conditions can cause peeling, dullness, cloudiness, or slow drying that leads to customer callbacks.
This guide explains the ideal conditions for uPVC spraying, how temperature affects the coating, and practical tips for avoiding common weather-related painting problems.
Why temperature matters when painting uPVC
Temperature is one of the most critical factors influencing paint performance. Since uPVC is non-porous, coatings rely entirely on adhesion and correct curing. If temperatures are outside the ideal range, the finish can fail, leading to callbacks, uneven gloss, or peeling.
Temperature-related problems can include:
- Poor adhesion and weak bonding
- Uneven or patchy gloss
- Runs, dry spray, or orange peel texture
- Extended drying times attracting dust
- Reduced long-term durability
ZebraCoat top tip: even small deviations from ideal conditions can affect your finish, check temperatures carefully before painting.
Ideal uPVC spraying temperature range: 10°C – 25°C
Spraying uPVC in a 10°C–25°C environment ensures optimal paint performance. Within this range, solvents evaporate evenly, coatings level out smoothly, and the gloss sets consistently.
Key benefits for trade professionals:
- Strong surface adhesion, reducing callbacks
- Smooth, even flow-out
- Consistent finish
- Reduced risk of sagging or dry spray
- Reliable long-term durability
Problems with spraying uPVC in temperatures under 10°C
Low temperatures significantly impact curing and adhesion. Painting below 10°C can slow drying, increase condensation risk, and result in a milky or cloudy finish.
Cold-weather issues can include:
- Adhesion failure or weak bonding
- Extended drying and curing times
- Milky, cloudy, or dull finish
- Increased chance of surface moisture causing long-term failure
ZebraCoat top tip: in winter, even seemingly dry surfaces can retain hidden moisture, so ensure surfaces are fully dry before painting.
Problems with spraying uPVC in temperatures above 25°C
High temperatures cause paint to flash-dry, which prevents it from levelling properly. Surfaces exposed to sun can be 10–15°C hotter than the air, creating problems even when ambient temperatures seem fine.
Hot-weather issues can include:
- Dry spray or rough texture
- Solvent popping and surface imperfections
- Inconsistent gloss levels
- Overspray drying mid-air
ZebraCoat top tip: avoid painting in direct sunlight or on very hot surfaces to prevent poor finish.
How humidity can affect your uPVC spraying results
High humidity slows curing and can cause blushing or cloudy finishes. Professional sprayers should aim for humidity below 70% whenever possible.
Humidity-related problems can include:
- Blushing (milky or hazy coating)
- Extended drying and curing times
- Gloss level inconsistency
- Poor adhesion
ZebraCoat: early mornings, fog, and post-rain conditions often have high humidity, wait for drier conditions to spray.
How sunlight and shade effect uPVC spray finishes
Direct sunlight can drastically increase uPVC surface temperature, leading to flash-drying and poor flow-out.
Trade tips:
- Spray in shaded areas whenever possible
- Work early morning or late afternoon in summer
- Monitor surface temperature, not just air temperature
ZebraCoat top tip: avoid midday sun; a shaded area ensures a smooth finish.
How to Check conditions properly
Professional sprayers use tools to monitor environmental conditions.
Recommended tools include:
- Surface temperature gun
- Humidity meter
- Weather apps for dew point
- Microfibre cloth to check for invisible moisture
Why ZebraCoat uPVC paint performs better across conditions
ZebraCoat uPVC coatings are engineered for professional trade use. They are formulated for fast-drying, strong adhesion, and high-gloss results, even in variable weather conditions.
ZebraCoat benefits:
- Trade-quality formula with reliable flow-out
- Excellent adhesion and UV resistance
- Over 30,000 colour options
- 10-year warranty when applied via approved process
- Designed for durability in real-world UK weather
Using high-quality products with proper conditions ensures long-lasting, professional results every time.
Explore ZebraCoat uPVC paints now or contact our team for expert advice.
About ZebraCoat: Professional uPVC coatings experts
ZebraCoat is a UK-based specialist in high-performance uPVC paints and coatings, trusted by trade professionals, manufacturers, and decorators across the country. With decades of experience in the industry, Zebra Coat provides products designed to deliver durable, high-gloss finishes that stand the test of time, even in challenging weather conditions.
Why trade professionals choose Zebra Coat:
- Trade-Quality Formulation: Fast-drying, high-adhesion coatings that level smoothly for a factory-like finish.
- Extensive Colour Range: Over 30,000 colours, fully customisable for any project or client specification.
- Proven Durability: Formulated to resist weathering, fading, and UV exposure, with a 10-year warranty when applied via an approved process.
- Professional Support: Expert advice, technical guidance, and training for decorators and spray professionals.
- ZebraCoat combines high-quality products with industry expertise, helping trade professionals achieve consistent, long-lasting results on every uPVC refurbishment or spraying project.
Final tips for perfect results year-round
- Avoid spraying below 10°C or above 25°C
- Monitor humidity and dew point carefully
- Always clean, degrease, and abrade surfaces before spraying
- Check surface temperature, not just ambient air
- Use shaded areas to avoid rapid surface heating
FAQs
- Can I paint uPVC in winter?
Yes, but with caution. For professional results, the ambient temperature should stay above 10°C, and surfaces must be fully dry. Cold conditions can slow drying, reduce adhesion, and lead to a milky or cloudy finish. Using heaters in controlled environments or spraying indoors can help maintain optimal curing. - Does humidity affect uPVC paint?
Yes. High humidity slows curing, causes blushing, and can reduce adhesion. Ideal humidity is below 70%. - How long does uPVC paint take to dry?
Drying time varies with temperature and humidity. At ideal conditions (10–25°C, <70% humidity), touch-dry is typically within 15-20 minutes for the 1k ZebraCoat, with full curing in 24–48 hours. - Do I need special tools to spray uPVC professionally?
For trade professionals, using the right tools is essential for consistent, high-quality results. A spray gun, surface temperature gun, and humidity meter help ensure proper adhesion, flow-out, and curing, delivering a professional finish every time.
Ready to get the best results?
For expert guidance, colour advice, or product support, contact our Zebra-Coat team today:
Email info@zebracoat.co.uk, call 01782 209527 or visit our Stoke Trade Centre, Units 6 & 8, Britannia Park Industrial Estate, North Rd, Stoke-on-Trent ST6 2PZ