Darkroom light tight fan?

I was just browsing Ebay over my morning coffee and came across the

following item. (1949724512 amd no..it is not mine nor do I know this

person). I have always thought that a light tight fan would be built

in such a manner as to not permit light through it. From the picture

on this one it is quite obvious that light can easily pass through.

Am I wrong? How is a light tight fan constructed?

 

On a side note I won a Vivitar Process Time Commander (darkroom

timer) on Ebay awhile ago and it does not seem to work properly. The

numbers come on but I am unable to program it to do anything useful.

I will not re-sell on Ebay and cause someone else the trouble but if

there is a fellow LF shooter out there that wants this thing , they

can have it by emailing me. All you need to do is pay for the postage.

 

Regards,

I have a very similar fan in my darkroom and it looks like he has left one of the louvers off of the fan for illustrative purposes. Basically there are two overlapping louvers that block the light. If you are venting into a pipe that bends to the outside, then one set of louvers can be taken off for increased flow. I have had fans in my darkrooms for many years. I have placed them over or near my sink. In my current darkroom I also installed a good bathroom exhaust fan directly over my proccessor (Fujimoto CP-51) that very nicely removes odors and heat from my darkroom. I leave the fan over the sink on at all times and it keeps air moving through the darkroom and greatly improves the environment. Just recently after almost 5 years the fan started to complain. I took off the cover and sprayed some WD-40 on the motor, end of complaint. If you are interested in the fan you should probably e-mail the seller and find out if both louvers are include in the sale. Sorry to hear about your problem with the timer. Did you attempt to return it to the seller? I have found that most people are willing to take back DOA items to protect their feedback ratings.

Cheers,

Go back to the seller and let him/her make it right. Many times these individuals may not have any experience to know if something works of not and if it does not it is not your problem and you should not take the hit. Feedback is very important in this process and ignoring it is your fault. One piece of important advice for all of us - Read carefully the fine print in all auctions and be cautions for any that are NO RETURN - ALL AUCTIONS FINAL.

Before this thread turns into a "runaway Ebay thing" let me clear something up front. I'm asking about how a darkroom fan works. The timer was just a quick side thought as I was typing. The seller described it as "working to the best of his knowledge" but that was limited. I'm OK with the fact that I took the chance and this is how it turned out. I just do not want to send it to somebody else with them believing that it will work right out of the box without a hitch. Maybe it is something I am doing wrong (no instructions) or maybe it is just that there is something wrong with the timer. I do not know. I do know that if nobody else wants to fiddle with the thing it's heading for the garbage can. :>))

I purchased my fan through a local hardward store; it's the most powerful one they offered for a kitchen, or whatever. After fastening the fan to a 5" or 6" duct, I maneuvered the duct through a 180 degree turn and painted the insides black. It's plenty light-tight.

If I may suggest my own approach to light-tight fixtures.

 

One of the posters mentioned " 2 layers of overlapping louvers". While this may be OK, in my view it is not the best solution. Dual-layer louver will only be light-tight if the louvers are very wide so as to have large overlapping area. To achieve that the active cross section left in between used for venting is relatively small. This may also lead to noise problems which is relative to fans speed and/or output. I found that to be indeed a troubling point in some of the commercially available darkroom fans.

 

The fix is to replace the 2 layers with 3. They are all overlapping, with the two outer layers placed exactly opposite each other and the middle one overlaps the gaps (they are all painted flat black internally). This way louver pieces can be much narrower and the gaps wider. What this does is:

 

- increases the available free space between the louvers

 

- improves efficiency of the venting

 

- in most cases cuts down on the fan noise

 

One can convert any fan into a light-tight one with little effort and just basic skills.

 

I also use same technique for gravity vents (doors, walls etc.). Keep in mind to let as much air "in" as you let "out", unrestricted "in" is even better.

Well I had my darkroom built with two 5 inch kitchen exhaust fans and just covered them with the foam used for camera cases....no light leaks.