When acrylic-painted windows start sticking after being painted, it’s usually due to one or more of these common reasons:
1. Incomplete Curing
-
Acrylic paint dries quickly to the touch, but curing (fully hardening) takes much longer — sometimes up to 3-4 weeks, depending on the environment.
-
If the windows are closed too soon after painting, the paint layers can fuse together under pressure or humidity.
2. Paint-on-Paint Contact (Blocking)
-
Acrylic paint, especially if it’s not fully cured or if multiple coats are thick, can experience “blocking” — a condition where two painted surfaces stick to each other when pressed together.
-
This is especially common in windows where painted edges meet.
3. High Humidity or Heat
-
Humidity slows down drying and curing, and warm temperatures can make the paint softer, both contributing to sticking.
4. Too Much Paint in Moving Areas
-
If you painted into the seams, joints, or contact areas of the windows, excess paint can act like glue once dried and cause sticking or bonding.
5. Wrong Type of Acrylic
-
Craft acrylics or indoor wall paints may not be ideal for windows or trim — they remain softer than enamel or exterior-grade acrylic latex, which cure harder and resist blocking better.
How to Fix It:
-
Gently open the windows using a putty knife or razor blade to separate any sticking parts.
-
Apply a light dusting of talcum powder or wax (like paraffin or candle wax) to the edges to reduce sticking.
-
If necessary, sand the contact areas lightly and repaint with a thin coat of non-blocking paint or add a clear, hard non-blocking polyurethane sealant (check it’s suitable for acrylic and for use near windows).
-
For future projects, leave windows slightly ajar while drying, especially during the curing phase.