Question about red fibre washers

[MikeB]

The red fibre washers - such as those used to connect a toilet up to the mains water feed, etc - am I right in thinking that they expand slightly after installation? Twice over the last year now, when using red fibre washers in a joint, once with a toilet cistern and once with a new roof cistern ball valve installation, I've had a very slight 'ooze' of water out of the connection, which has disappeared after a while. Would this seem right to the expert plumbers out there?

Mike

[Rob graham]

AFAIK they don't expand after installation. The most likely explanation of a weep curing itself is that very small particles in the water block the hole as they emerge from it - a bit like Radweld in cars. It is very common for weeps to self heal even where there is no fibre washer.

Rob Graham

[MikeB]

Thanks Rob