UV-light for DNA linking and destruction

[M O L B I O L]

Dear all

Can anyone give me some explanation as to the proper wavelength for the 
following purposes:

 1) DNA cross-linking to nylon-membranes. There seem to be at least two 
wavelengths in use for commercial cross-linkers 254 and 312 nm. The goal 
naturally is to achieve the utmost efficiency in binding and high specificity 
in subsequent hybridization.

 2) Destruction of DNA. At several places I want to clean the working hood or 
labtable, and instruments like pipettes from DNA which would otherwise 
contaminate my PCR. However, I can imagine that the shorter wavelengths 
deteriorate all sorts of plastics and paint most. Furthermore, I like to now 
if perspex is totally effective in protecting me and my fellow-workers from 
UV of the proposed wavelengths.

ciao

Gabriel Zwart