A thangka is painted with mineral pigments on cotton that has been primed with chalk and glue, so it reacts to its surroundings more than most people expect. Strong sunlight fades the blues and greens first, and damp air can make the ground layer crack or grow mould along the edges. Keep it away from windows, bathrooms and kitchens, and do not hang it directly above a heater or an incense spot.

Dust is best removed with a very soft brush, lightly and in one direction, never with a wet cloth. If you have to store a scroll, roll it loosely with the painted side facing out around a wide tube and wrap it in clean cotton, not plastic, which traps moisture. Buy authentic thangka painting only after asking how the canvas was primed and whether the colours are natural minerals, since that tells you a lot about how well it will age.

Once a year it is worth unrolling or taking down the piece to check the back for insects and the silk mounting for loose threads. Small problems are easy to fix early, and a well looked after thangka can stay bright for several generations.