Fat free milk

[lulubel]

It's not only temperature - acidity in the coffee will also cause the soya milk to clot as it's a metastable colloidal suspension. So some typres of coffee are worse that others - needless to say, instant is OK, but Kenyan, Brazilian and other mild(-ish) coffees are OK, while I find Yemani, Sumatran, Javan and Cuban all too acidic for a stable mix. High roast also tends to clotting.

Instant is the only coffee I've had any problems with, unless I let the water cool a while before I made it. (Not that I drink instant any more if I can help it.) I don't know exactly what I drink, although I know it's a blend, because it's a "secret recipe" specially prepared for my brother's coffee shop. The coffee experts like guessing, and they all say it's a rich, dark blend - whatever that means