"safe" green light

John Hewitson 100600.70 at CompuServe.COM
Fri Nov 29 02:08:35 EST 1996


My solution to your problem has been to use a fluorescent tube wrapped in
theatre colour filter material, normally used for coloured floodlights or
footlights.  I use a 2ft fluorescent tube as it is easily portable with its
fittings attached.  I have used Chromagel (or Supergel) #90 "Dark Yellow Green".
It specification sheet shows that almost all its transmission is between 420nm
and 600nm, with a peak at 520nm; its transmission is only 13% and I have wrapped
my tube three times round with this material and secured it with tape.  It's
pretty dark when I use this light and I have to sit for a while before I can see

I have no evidence that the seeds "see" this light at all - the lettuce
experiment works much as predicted after using this light for a short time.

In US, a main supplier is Strand Lighting Inc, 18111 South Santa Fe Avenue, P.O.
Box 900, Rancho Dominguez, CA 90224.  Tel 310 637 7500, Fax 310 632 5519  - they
probably have local agents.

I visited our school theatre and was able to get as much as I needed "off the
roll".  Your local theatre will tell you the agent they use for their filter

However, for most purposes, I try to avoid using a safe-light at all and fumble
about in a light-proof bag wherever possible.


| Dr. John Hewitson                                                        |
| Berrystead Barn			    +44 (0)1832 272 209 phone/fax  |
| Oundle,                                                                  |
| Peterborough, PE8 4DY, UK 	     	  e-mail 100600.70 at compuserve.com  |

(Biology Department, Oundle School)

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