I have some Japanese woodcuts that have been framed behind Artglass. Not in a bright place. How much will the colours fade?

You’ve already got a lot right. There are obviously differences between hanging a picture in a museum and hanging it on your wall at home. In your own home, it’s not possible to exclude all daylight and live in very low light levels. Japanese woodcuts tend to be particularly sensitive to light, because they’re often made using organic colours. I’ve seen examples where it’s almost impossible to imagine what the colours were like when they were first printed. Filtering out UV light by using Artglass is a correct way of preventing fading. And you’re also right not to hang the prints in direct sunlight.

Beyond this, it’s almost impossible for me to make predictions about the degree and rapidity of fading in the conditions you describe. At the museum, however, we are getting better and better at making precisely these kinds of predictions, by using micro-fading technology. We use a device called a micro-fading tester (MFT) to measure how quickly changes happen, without them being visible to the naked eye. This technology allows us to be better informed when making decisions about how long works can be displayed and in what light levels. Light damage is cumulative and irreversible.

Kind regards from Alexandra, paper conservator