Hiking | choosing hiking jacket: what is waterproof rating?
A product is recognised as waterproof when it has the ability to stop rain getting through, thus protecting the hiker from bad weather and it is quality of the jacket is determined by the waterproof rating.
You need to know that there are different levels of waterproofing rating, and different tests to measure them.
In order to test the watering rating, first, the waterproofing of a fabric is given, and on the other, the waterproofing of an entire product is proven.
Check that in addition to using a waterproof material, your jacket has waterproof zips.
Two types of waterproofing rating test: water column vs shower
The water column test
This test measures the resistance of a fabric to water pressure.
The results of the test are expressed in mm of a water column or mm Schmerber (the name of the textile manufacturer Charles Edouard Schmerber who created this measuring tool).
1 Schmerber = 1 mm water column = 0.1 mbar .
Average rain pressure is in the range of 1000 to 2000 Schmerber.
It is therefore considered that a garment which resists the pressure of a 1.3-metre water column (i.e. 1300 mm) is waterproof (according to the standard ISO 811). But beware, a jacket designed with a waterproof fabric to the level of 2000mm Schmerber will protect you from the rain, but maybe not a downpour or a long storm.
Indeed, the higher the Schmerber rating, the more waterproof the material.
Please note: the quality of the fabric used is very important, as the waterproofing of a new jacket designed using poor-quality material may change after washing.
The shower test
This test is, in our view, the most representative, as a product designed with a very waterproof fabric will be able to take on water via its seams, flaps and zips, etc. In this test, the products are placed under a shower in order to test their overall waterproofing.
Different waterproof rating for different purpose.
After the test, the following classifications can be defined:
2000mm - protect you from *general rainfall
5000mm - protect you from heavy rainfall
10000mm - protect you from rain storm. ( you may feel painful when rain hit on your face)
15000mm - High pressure water column
*General rainfall between 1500mm - 2000mm
Of course, for your own safety, please check the weather forecast before you leave. In case the weather forecast shows that the weather is going to turn bad, consider changing or canceling the trip. If you suddenly encounter unpredictable bad weather on the mountain, please return to a safe place as soon as possible.
2000Mm -protect you from general rainfall
10000Mm - protect you from rain storm
15000Mm - longer protection
Be careful not to confuse waterproofing and water-repellency
We have seen that waterproofing represents the product's ability to resist the penetration of rain.
On the contrary, water-repellency is a fabric's ability to let water slide over its surface without seeping in. The water-repellent treatment is a treatment via coating which can be added to certain products: it can either be added to a jacket with a waterproof layer to improve it, or it can be added to a product which is not essentially waterproof. In the second case, it guarantees a temporary solution if you are caught out in the rain.
These products, such as the X-light padded jacket, are generally designed for a different function such as heat provision, and their water-repellency is just a "bonus", as they are not designed to protect you from the rain while hiking. A jacket which is only water repellent (and not waterproof) is only designed to ensure minimal protection, and it will be suitable for a "makeshift" use, so the best practice is check the waterproof rating on the label before you buy.
In the event of rain, consider putting on a 3rd waterproof layer. Owing to wear and tear, your jacket may lose its water-repellent property, so check out our recommendations on restoring it.