How to sand Jarrah window frames to paint?

[amylisa125]

Hello, I am sanding back varnished Jarrah window frame to paint white. How far back do I need to strip them. Can the varnish be imperfect as I’ll be priming and painting or do I need to strip all perfectly back to original state. Thank you. 

[MitchellMc]

Welcome to the Bunnings Workshop community @amylisa125. It's sensational to have you join us, and many thanks for your question about painting window frames.
 

It depends on how compromised the varnish is. Ideally, it’s best to sand it all back to bare timber for a fresh start, ensuring the best adhesion for your primer and paint. Any deteriorated varnish left behind could delaminate over time, which would affect the durability of your paint finish. If the varnish is still well bonded and in good condition, you might get away with just scuff sanding it to create a surface the primer can adhere to, but for the best long-term result, stripping it back completely is the way to go.

Please let me know if you have any questions.

Mitchell