Butterfly Buttress on Ruthin Escarpment is an extremely useful bouldering venue, primarily because it seems relatively immune to the usual limestone dampness issue. Another factor in its favour is the strong collection of quality problems that it boasts.
The climbing takes place around the undercut base of the buttress with most problems finishing at a jump-off-able height. There are quite a few grade 6 problems but to get the most out of the place it would be best to be comfortable on grade 7s. The landing is fairly flat, but quite rocky so pads are essential.
The crag stays remarkably dry during wet periods; however a towel is useful to cover the occasional wet starting foothold. It gets the afternoon sun and is very sheltered. Year round climbing is possible, indeed there will be times, particularly during the winter months, when this is one of the only places in North Wales where you will find dry rock.
As you arrive in the village of Pwllglas park immediately on the left in the lay-by (assuming you have come from Ruthin). Walk 100m back up the road (in the direction of Ruthin) and drop down a small road/track on the right. Follow this across the river then around a left hairpin and up until a path is seen on the right – follow this path rightwards for a few hundred metres before cutting up through the trees to reach the crag.