I guess we all tend to waste a lot of effort on half-resolved ideas and experiments which end up buried in sketchbooks or discarded on the back of scrap envelopes. Some while ago I went to a short workshop on natural geometry, and had a lot of fun with compass and ruler revisiting the only bits  of maths O-level that really chimed with me (that and drawing nets). I tucked the notes in the cupboard and forgot all about it, until I broke the tile lid of a wooden box and decided to paint a gesso panel to replace it: an ideal opportunity to revisit the notes and do a little exercise in combining 'fourness' and 'threeness' in the manner of a medieval rose window. Jolly difficult too - not quite up to the standards of the cathedral architects yet, but at least the effort has not entirely gone to waste.

For thousands of years lead white (lead carbonate or cerussite) was the only brilliant and opaque white pigment available. Nowadays the inert titanium dioxide has supplanted it in food, cosmetics and household paints for obvious reasons. However, many artists swear by its very special handling properties, and it is an indispensible plasticising constituent of the gesso used in manuscript gilding. It is difficult to obtain genuine lead (flake) white these days because EU legislation tightening up the rules for producing such toxic substances is making it sub-economic to commercial pigment producers. Word is that it will soon be equally difficult to obtain in the US. So when we can't buy it any more what will we do? It is simple to make yourself: follow the link below and check out this fascinating YouTube video demonstrating how by US pigment maker Attila Gazo of Master Pigments. But if you do fancy having a go, be warned - lead white is extremely toxic even in small quantities and poisoning is irreversible. Don't put your rinsings down the drain either.

https://www.youtube.com/watch?v=IKWgD0dLLls

Today I finished an illuminated piece which I have been hanging fire on a long time, not knowing how I would manage the lettering. I've had several attempts at learning 'proper' calligraphy over the years, even with a tutor, which have mostly left me dishevelled, inky and frustrated. Finally I decided to use my mapping pen and work in my own adaptation of versals (inked in outlines): I swiped the design for these from the incomparable Klosterneuberg altar frontal by 12thC enamellist Nicholas of Verdun. Not perfect - I can just hear that calligraphy tutor now - but legible at least. The painted design is another homage to 12thc Armenian illuminator T'oros Roslin. This prayer of St Ephraim the Syrian, called the Lenten Prayer in the Orthodox Liturgy, is a favourite of mine. The support is natural calfskin vellum: I have been practising on vellum for a while, it is a touchy material but very rewarding. I used walnut ink made from crystals imported from the US (good old Ebay), gold leaf (of course), and mineral pigments including lapis lazuli and volksonkoite. On balance this was a mistake as their crystalline texture makes it very difficult to achieve the smooth surface needed for accurate top painting. Our medieval forebears must have had minions to grind their pigments much finer than the finest available today. For the medallion icon I used raised and burnished gilding, which is not historically accurate to the style of the manuscript decoration (in Eastern manuscripts only flat gilding was used), but then I wasn't intending a reproduction.

This exquisite interior is St Stephen's Walbrook, a Wren church in the heart of the City of London. The Society of Catholic Artists have an exhibition there until 27th November. and I am lucky to have my icons in the perfect spot next to the original altar. The light was pouring through the windows above, hence the grainy photograph. The church deserves a visit even if you are not purchasing art. The eighteenth century box pews have been replaced with a magnificent altar sculpture by Henry Moore, making a church 'in the round'. It is surrounded by tapestry kneelers designed by abstract artist Patrick Heron, which remind me of Matisse's papercuts.  Some magnificent paintings for sale in the show, in all styles from figurative to abstract and in all sizes from a few inches (mine!) to an eighteen foot triptych. Open weekdays 10 till 4, and at weekends during services. Nearest tube Bank or Cannon Street.