thanks to all those who are contributing. it seems some would rather debate the right and wrong of screw verses cap. if that could be put in another tread that would be great. although you will all do what you will.
Am vey interested in finding out more about the cap on cap. or seal. will look into it.
also would like to make it very clear that i did not start this tread as a means to a comercial enterprise! so if you could avoid that too.
(sounds very demanding dosen't it)
Thanks again for letting me gather info from here.