Shop Orchid Care OrchidTalk Orchid Forum Weather Station Links Nursery

Welcome to OrchidTalk Orchid Forums

The Friendliest Orchid Community on the Internet!

  •  » Learn to Repot your Orchids
  •  » Learn Orchid Care Tips and Secrets
  •  » Find the perfect Orchid for your Growing Environment
  •  » Chat with Orchid Growing Professionals

OrchidTalk - "Bringing People Together to Grow Orchids Better!"

Let us help you grow your Orchids better; Join our community today.

YES! I want to register an account for free right now!

Register or Login now to remove this advertisement.

Results 1 to 2 of 2

calibrating a hygrometer (for measuring humidity)

This is a discussion on calibrating a hygrometer (for measuring humidity) within the Orchid Forum Articles forums, part of the TalkTalk category; Not sure if this is really the best section to post this under, nor how ...

Click here to increase the font size Click here to reduce the font size
  1. #1
    pavel's Avatar
    pavel is offline change is the only constant
    Favorite Orchid(s)
    whatever will bloom
    Join Date
    May 2005
    Member's Country Flag

    Default calibrating a hygrometer (for measuring humidity)

    Not sure if this is really the best section to post this under, nor how many folks, if any, might have a use for this info but found it via another forum..........

    How to Calibrate a Hygrometer

    by Lianne McLeod, DMV

    To calibrate a hygrometer you will need:

    • 1/2 cup table salt
    • approximately 1/4 cup water
    • coffee cup
    • hygrometer
    • large re-sealable freezer bag

    1. Place 1/2 cup of salt in the coffee cup, and add the water. Stir for a bit to totally saturate the salt (the salt won't dissolve, it will be more like really wet sand).

    2. Place the salt/water mix in a re-sealable plastic bag, along with the hygrometer, and seal the bag. Note: make sure none of the salt/water mix comes in direct contact with the hygrometer.

    3. Let this bag aside at room temperature for 8-12 hours, in a location where the temperature is fairly constant.

    4. After 8-12 hours, check the reading of the hygrometer. It is best to read it while still in the bag.
    The relative humidity in the sealed bag with the salt/water mix should be 75 percent (mine read about 72 percent).

    5. For adjustable hygrometers, adjust to read 75 percent. You will have to do this very quickly, or remember how much you need to adjust the setting (e.g. mine read 72 percent rather than 75 percent, so I would need to adjust the dial up 3 percentage points).

    If yours is not adjustable (like mine), simply make a note of how "off" your hygrometer reads. If it reads below 75 percent, you will need to add the difference to your actual readings. If your hygrometer read above 75 percent on the calibration, you will need to subtract the difference from your actual reading.

    In my example: after sitting in the bag, my hygrometer read 72 percent, when it should have read 75 percent -- a difference of 3 percent. I now add 3 percent to the readings I take on the hygrometer (e.g. in a tank) to get the actual relative humidity.

    Remember: always give a hygrometer about 2 hours to stabilize before taking a reading, as changes in the relative humidity may take a while to register accurately on a hygrometer.

  2. #2
    Brutal_Dreamer's Avatar
    Brutal_Dreamer is offline Dreaming with my eyes open...
    Real Name
    Bruce Brown
    My Grow Area
    Favorite Orchid(s)
    Cattleyas & Slippers
    Join Date
    Mar 2003
    Member's Country Flag


    Thanks, Paul! I updated the thread title for you. This is great information.


Similar Threads

  1. humidity help
    By OrchidTraci in forum General Orchid Culture
    Replies: 6
    Last Post: April 20th, 2010, 12:46 AM
  2. Hygrometer & other supplies
    By nicki in forum General Orchid Culture
    Replies: 3
    Last Post: February 25th, 2009, 09:01 PM
  3. Humidity
    By nabakov5 in forum General Information
    Replies: 5
    Last Post: September 4th, 2006, 01:32 PM
  4. Humidity
    By starwhiz in forum General Orchid Culture
    Replies: 6
    Last Post: July 11th, 2005, 02:07 AM
  5. slc vs blc and humidity
    By RSJ in forum General Orchid Culture
    Replies: 3
    Last Post: January 12th, 2005, 09:51 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
OrchidTalk --An Orchid Growers Discussion Forum brought to you by River Valley Orchidworks. A World Community where orchid beginners and experts talk about orchids and share tips on their care, cultivation, and propagation.