Martin wrote:
I can see that icing in the freezer is linked to air leakage past the top of
the door seal. As the seal contains a magnetic strip embedded in
plastic, I can't envisage what could possibly wear or age over time, which
makes me think it would be pointless replacing the seal; there are no moving
parts and I doubt the magnetic strip loses its effect over time.

So do these door seals lose their capacity to seal over time and, if so,
what is the mechanism of this ageing/wear process?

Thanks

Martin



Yes they do wear out by the simple loss of magnet strength. They are not
very powerful to begin with (think door which can only be opened by a
weightlifter) and the technology which embeds metal particles in a
flexible substrate may not offer the longest life. But it is possible
that the seal is not the problem -- if it is then the strength should be
lost fairly uniformly over the whole seal. Sometimes it is a matter of
misaligned hinges or even a warped door (think child swinging on door)
so if the leakage seems to be in only a limited area that might your
problem. The old dollar bill test still seems to be the standard for
checking seals. If one had access to a hall-effect gauss meter then a
more scientific check of the seals magnetic force could be done but I've
never seen one outside of a laboratory.

--
John McGaw
[Knoxville, TN, USA]
http://johnmcgaw.com