1. Insufficient dry of Putty
2. Unsmooth sanding on the edges of surface which are not properly blended with previous film
3. The Thinner evaporates too slowly
1. Mix the Putty and Hardener in a proper proportion. Allow the Putty to dry perfectly before proceed to next step.
2. Do not top the Putty over old paint film, especially on the fast-drying type.
3. Adjust the viscosity of paint and use appropriate Thinner.
Once the surface dried thoroughly, sand and prepare before applying a slow-drying primer (Urethane) and refinish.