Causes for a weathering on exterior wood
Improper treatment can quickly lead to flakey surface finish. Here are some possible causes.
Wood extractives are not weathered off. The wood was saturated; the oils could not penetrate deeply enough and did not bind with the wood from inside.
Release film on the surface. A release film (e.g. resins and dirt) have prevented the necessary penetration and have strongly reduced the adhesion.
Excessive moisture absorption. Through improper constructional wood protection (e.g. waterlogging, screw holes within grooves, unprotected cut edges), water is absorbed through capillaries and infiltrates the treated wood.
Wood moisture content at the time of application was too high. The oils could not penetrate the damp wood sufficiently and therefore they cannot bind with the wood from inside.
If too much oil is applied, the pores will clog up and a layer will form. The result can be flaking or peeling. Therefore always apply oils thinly and evenly.
