Reply To: The painting of blocks in the Royal Navy.
For those vessels with wooden blocks my best experience is using Deks Olje D1 Wood Oil, soaking the wooden shells thoroughly, & then hanging them up to dry, before reassembling. This creates a smart matt finish, which is robust, lasts well, and is very easy to repeat when servicing next comes around on the schedule.
D2 leaves lovely gloss finish, but like marine varnish this cosmetic good look is achieved at the expense of longevity & practicality. D2 & Varnish do not stand up to rough & tumble, or UV for that matter, and you need to scrape off remnants & prepare surface before re-doing, all of which takes unnecessary time.
Some traditional sail training ships paint their wooden blocks, but that is inefficient & hides rot. On the plus side, it creates uniform appearance, and is quick to do.