Wood filler is porous. You must seal it with a high-quality primer before applying your exterior-grade topcoat. This ensures the patch remains hidden and protected from UV rays. Pro Tips for a Flawless Finish
If you are reading or writing this post, these are the high-value nuggets of information that make it worth the read: wood filler window sill
These are easy to clean up and work well for minor cosmetic issues. Low odor and eco-friendly. Wood filler is porous