This should answer all your questions: it's right here on the CLC website...

http://www.clcboats.com/shoptips/epoxy_and_fiberglass/

 Chris F

1. Leave them screwed on

2. Should be good for at least a year, much more if the container is stored in a cool dark place. I've successfully used 5 year old System 3 epoxy/hardener.

3. Some folks clean them with vinegar, I throw them away and buy new ones every year or so. Life is too short to spend on cleaning pumps, especially cleaning out the cleaner so it won't contaminate the epoxy/hardener. The epoxy pump usually just needs to be warmed above 140 degrees for a while to get rid of crystals, the hardener pump is what usually needs the vinegar.

And if this is like every other epoxy pump thread, someone will jump in saying how much better measuring cups and/or scales work than pumps. I've used both and haven't had problems with either, so my recommendation is to go with whichever is more comfortable to work with.

Have fun,

Laszlo

I'll second Laszlo.  I used my pumps for the entire build which took 8 months.  Pumps still working great, never a problem with the mix.  I never cleaned them.  I kept them in a box and during extended times between use i put the box in the basement.

Rod

Thanks for the replies folks!

 I figured this wouldn't be a huge problem, but this is my first venture using glass and epoxy, so I wanted to be sure.

Paul

When I did use the pumps, I didn't find it necessary to clean between uses, because I went through the epoxy fairly quickly.