On Sun, 14 Mar 2021 21:39:54 -0400, micky
wrote:

My house was built when formica counters were't rolled at corners but
there were saparate pieces on tops and sides.

The bathroom counter got wet and I didn't dry it for 10 or 15 minuters
and even then I might not have done a perfect job, and it swelled.

But only a little, and it seems to have gone back** so close to the
original size I can barely notice.

I need to waterproof the corner edge.

What should I use????



**Unlike my kitchen counter. I had a plastic bottle of distilled water
on the cement basement floor for months, without its leaking at all.

When my friend who only drinks distilled water was about to arrive, I
put the bottle on the kitchen counter and the next morning the counter
had a puddle on it and the particle board inside had started to swell.
It got worse in the next day, both vertically and horizontally, and
never shrank again, afaict not at all.

That had to be replaced, but the bathroom counter, well, maybe I could
tell if I looked at, but I'd rather not look and imagine that it's
perfect again. :-)

The real answer is don't use particle board for counter tops but that
ship sailed. CDX is better than sawdust and glue but a good exterior
grade of plywood is better.
The only mica I have here is a small round table in the pool bar. This
has been living outside for over 30 years and it is OK. I sealed the
edges of the plywood with poly before I glued the mica down and it is
doing fine. I can't say as much for the oak flooring I put on the bar.
I ripped that off and put granite on it.

http://gfretwell.com/electrical/TIKIBAR.jpg

The best mica job I ever saw was in a house we rented in Montana.
They cut the corner out with a router, laid in a piece of Corian and
rounded it over. That eliminates the chipped edge problem.

http://gfretwell.com/ftp/counter%20edge.jpg

I did a similar thing in the master bathroom here but the counter top
is tile. The edge is Corian.