Acrylic and moisture

[Harry Bloomfield]

Does anyone know whether acrylic is totally impervious to water please?

I believe it is....

Reason for the question is that caravans use two panels sealed together as a form of double glazing, not fully sealed, they have a pair of removable bungs. The problem is that under certain contains moisture trapped between the panels can condense out on the inner or outer pane causing misting. One suggestion is to remove the bungs on a warm dry day, then re-seal after venting. Another suggestion is that any moisture can migrate through the acrylic panel anyway, so removing the bungs is a waste of effort.

[Nightjar]

Not totally. It will slowly absorb some water, gaining about 1% in weight after a month of total immersion.

Take the bung out. Thin acrylics, such as floor sealants and paints, have a certain amount of permeability to water vapour. Acrylic glazing sheet can be considered as essentially impervious. The people who think it is migrating have a leak somewhere.

Colin Bignell

[Harry Bloomfield]

Thanks, that is what I thought. Not a leak, so much as that there is moisture in the air trapped inside. The suggestion was that the moisture would migrate out given time.

[Andy Champ]

Actually you should remove them on a _cold_ dry day, which is when the absolute humidity is lowest. Applying a hair-drier to the sheet might encourage things.

A warm dry day can have a surprising amount of water in the air - which is why you get all that condensation. You know, the big white fluffy things in the sky?

Andy