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Inside The Outdoors
Your guide to IsoDry Waterproof

Your guide to IsoDry Waterproof

09.10.2015 | Expert Advice

What is Isodry?

ISODRY is an advanced technology unique to Mountain Warehouse, which can be found in a variety of products such as waterproof shoes and coats. Isodry is a waterproof and breathable lining constructed of a membrane which is fully waterproof but porous. ISODRY fabric permits perspiration to pass through one side but not the other so moisture will be wicked away but rain will not enter.


What do Waterproof ratings mean?

Waterproof ratings are measured in millimetres, tested by manufacturers using a hydrostatic head test. How waterproof an item is represented by its waterproof rating. The higher the waterproof rating the longer your item of clothing or shoes will withstand rainfall. When a product is tested to see if it is waterproof or not, the product will need to meet the British Standard, which means it must have a waterproof rating more than 1,500mm. So how does a hydrostatic head test work? The test is carried out using a piece of material that is pulled taught below a 1 inch diameter sealed tube of water. The fabric will be closely monitored over a twenty -four hour time frame to find out how many millimetres of water the fabric can endure before the water leaks through.


How do I know what waterproof rating I need?

Firstly, to meet your needs you will need to know what you will be using your waterproof wears for and how long you will be wearing it for. Usually items with a waterproof rating of 1,500mm to 2,000mm are often used for general use, as you are less likely to get caught out in bad weather for long periods of time. If you’re a serious walker, or regular dog walker it is suggested you wear a waterproof rating of 5,000 to 10,000mm. The higher the waterproof rating the better breathability, so when active it is advised your outerwear has a high breathable membrane. However when in heavy rainfall for long periods a 10,000mm waterproof rating is preferred to cope with extreme weather conditions and keep you dry for longer.


More about how waterproofness is measured.


What is the difference between waterproof and showerproof?

There are two different types of ‘waterproof’ categories- fully waterproof and showerproof, often referred to as water resistant. So what makes an item fully waterproof? For a product to be completely waterproof it will need to have taped seams. Taped seams are heated sealed seams that prevent moisture from entering or escaping so the more taping, the less breathable an item will be. It is advised to choose an item that is fully waterproofed  such as ISODRY clothing if you will be in heavy rain.

However a showerproof or water resistant product will not have taped seams and it will be non ISODRY, but will be treated with Durable Water Repellency coating (DWR), or something similar. When an item is treated with DWR it will be noticeable, as the water will bead off the surface. If the water does not run off the surface of the material then you will know the water repellent coating has worn off and therefore you will need to re-condition your item. With a showerproof or water resistant item of clothing or shoes, it is suggested that they can only withstand light showers for up to thirty minutes, or you may get wet.


Isodry Extreme 3 years Waterproof guarantee

We are so confident that our ISODRY Extreme wear will weather the storm that we promise our products will remain waterproof for three years. When purchasing your ISODRY Extreme product you will be advised to register your product- if your product is eligible for the Extreme three year waterproof guarantee you will see this red label attached to the product.


Looking for a waterproof jacket? Have a look at our guide – How to choose a waterproof jacket to help you make the right decision.