Some of the cracks look like de-lamination, some appear to be deep 'checks'. I have encountered similar severe checking on cabin-top teak
handholds. I filled the cracks with 'Loctite PL premium' construction adhesive
, available at hardware
stores in caulk gun tubes. I forced the goop in with a plastic spatula then pushed it in very hard with a folded piece of clear 'glad wrap' using my hand. It gets everywhere on the wood surface but, keep it very thin (outside the cracks) to save on sanding
. The stuff expands slightly when it hardens so it is great at filling deep cracks. I then sanded the hardened filler after 24hrs back to the wood surface and painted with cetol (luckily it is tan colored); varnish
might be better. The preceding also worked on my badly checked, pressure treated, mailbox post and my roof fascia boards. I top-coated those latter items with house paint
. It is a very weather
resistant repair when painted (do not expect UV resistance), the fascia repair is >12 years old, with no problems observed.