Lightproofing Exhaust Fan

Using a typical bathroom fan, does putting two 90 degree bends in the
exhaust pipe/tube eliminate light coming in from outside? Also, does
anyone have any creative inexpensive ways of keeping b&w chemicals at
an apropriate temperature? I'm thinking a heating pad on low under the
trays might do the trick?

"Jeph" wrote in message
oups.com...
Using a typical bathroom fan, does putting two 90 degree bends in the
exhaust pipe/tube eliminate light coming in from outside?

Something similar worked with my set-up. I made up a simple labyrinth, and
painted all internal surfaces black.

Also, does
anyone have any creative inexpensive ways of keeping b&w chemicals at
an apropriate temperature? I'm thinking a heating pad on low under the
trays might do the trick?

I used a small (~ 15" sq ) bed heating pad with different thicknesses of
newspaper between it and my dishes to get the correct temp. (I was relying
on the overheat thermostat to work so perhaps not so recommendable, but it
was certainly cheap! and nasty.)

--
M Stewart
Milton Keynes, UK
http://www.megalith.freeserve.co.uk/oddimage.htm




--
Posted via a free Usenet account from http://www.teranews.com

"Jeph" wrote in news:1150052848.629475.265690
@i40g2000cwc.googlegroups.com:

Using a typical bathroom fan, does putting two 90 degree bends in the
exhaust pipe/tube eliminate light coming in from outside?

Yes. Light travels in straight lines, so having two 90 deg bends assures
that light cannot come in via the exhaust duct.

Of course, the duct material itself should be light tight so that the bends
will form an effective light trap.

Also, does
anyone have any creative inexpensive ways of keeping b&w chemicals at
an apropriate temperature? I'm thinking a heating pad on low under the
trays might do the trick?

I don't bother. I just process at room temperature.

Jeph wrote:

... 90 degree bends in the exhaust pipe/tube eliminate light
... I'm thinking a heating pad on low under the ...


A baffle at the exhaust should do. Check out seed germinating
heat pads. I think they operate in the correct range. Dan

In article .com,
Jeph wrote:

Using a typical bathroom fan, does putting two 90 degree bends in the
exhaust pipe/tube eliminate light coming in from outside? Also, does
anyone have any creative inexpensive ways of keeping b&w chemicals at
an apropriate temperature? I'm thinking a heating pad on low under the
trays might do the trick?


A couple of decades ago, I had a commercial product that consisted of a
flat, rubber coated heating pad that went in or under the tray or other
container, a sensor that clipped onto the side, plus a (non-calibrated)
control knob. I can't for the life of me remember the brand; it was a
little expensive but worked well - to within a degree or two.

Probably long gone, but anyone else remember this better?

I would stay well away from using a standard heating pad with
chemicals. Too dangerous, and not enough control to be worthwhile. You
might want to explore items intended for aquariums or reptile
enclosures. some of these use a flat pad that sticks to the underside
of the tank; probably not wqterproof but at least splash proof.

Or just keep the whole room at 68F.

For light-proofing, spray the inside of the bends with flat black
paint. Also, spray the connection points to the exterior wall. This
will reduce any light leaks spreading by reflection. Additionally, if
your coupling to the exterior is plastice, it will be transluscent in
daylight if not blackened.

Jeph wrote:
Using a typical bathroom fan, does putting two 90 degree bends in the
exhaust pipe/tube eliminate light coming in from outside? Also, does
anyone have any creative inexpensive ways of keeping b&w chemicals at
an apropriate temperature? I'm thinking a heating pad on low under the
trays might do the trick?