hair hygrometer
Posted: Thu Nov 05, 2015 10:01 am
Has anyone found that the dime for the weight for the hair hygrometer is too heavy? What else can be used? Or are we doing the experiment wrong? 
Hi,
If you followed the instructions on the project page (https://www.sciencebuddies.org/science- ... #procedure) then you made the hygrometer correctly and it should show measurable differences in length between 0% and 100% relative humidity.
You didn't say what happened. Did the pointer not move when you put the hygrometer in a box with 100% humidity? Did you try using a lighter weight? The hair is supposed to get shorter when the air is dry and then lengthen as the humidity rises, so there has to be enough weight to straighten it out, but not so much that the hair can't pull back up when it gets drier.
Some people's hair may show more of a change in length than other people's, so try a couple of different hair types and see if that helps. Some people have also used hair from a horse's tail if you happen to have access to horses. Just remember to clean the hair with rubbing alcohol before you use it. I don't know if bleaching or coloring hair affects the way it reacts to moisture, but you might want to try natural hair just to be sure.
Please let us know what you find out so we can know how to deal with this problem best in the future.
Good luck!
Sybee