With Spring just around the corner and April showers a looming threat, good waterproof gear is a must. Whether it’s a jacket for getting from A to B, or trousers for added wet weather protection out on the hills, we’re here to guide you through the mystery of hydrostatic head, and give you a rundown of waterproofing technologies from our leading brands.
So... What is hydrostatic head?
Hydrostatic head (HH) put simply, is a measure used to assess how waterproof an item is. HH is measured by covering the bottom of a tube with the material, the tube is then filled with water. At the point where water begins to leak through the fabric, the height of the water in the tube is measured (usually in millimetres) and this is the measure of hydrostatic head. If, for example, the water in the tube is at a height of 2000mm, this is the HH of the fabric. For an item to be classed as waterproof it must have a minimum level of 1500mm, however this is a very low figure compared to the levels of big brands.
Most waterproof products will have something coating the outer fabric called a DWR, or Durable Water Repellency - this is the stuff that makes water bead off your jacket. If you start to notice water soaking into your jacket or ‘wetting out’ this means the DWR coating needs reproofing.
Where does breathability come into it?
Chances are, you’re going to be active in your waterproof jacket, even a leisurely walk can generate heat and result in unwanted sweat. The last thing you want is for any moisture to be trapped in your jacket, that’s when breathability becomes especially important. Breathability allows the release of vapour, working to keep you dry whatever your level of activity is.
Along with a measure of hydrostatic head, most technologies have a measure of breathability too. This can be measured through how many grams of water passes through a square metre of fabric over 24 hours. If a material has a measure of 10,000, it means 10,000g has passed through the material, the higher the number, the higher the breathability. Alternatively, a RET rating (Rate of Evaporation of a Textile) can be used, which is the level of resistance a fabric puts up against evaporation, i.e. the lower the RET level, the better the breathability.
A Note on Reproofers
There are a lot of products to help reproof your waterproof kit and whilst it’s always a good idea to clean and reproof your waterproofs regularly to get the most out of your kit, reproofing products will only enhance the DWR coating on the outer fabric of your gear. This in turn helps the breathability, as if the outer fabric is wet then no moisture can pass through it to escape.
It’s quite common to wash your products frequently using specialised products, but it’s worth noting you don’t have to reproof your gear after every wash, only when you notice your DWR not working as it should do. Some reproofers require heat activation, i.e. putting your product in the tumble dryer to ‘activate’ the DWR. Grangers advise that you do apply heat to your products after you’ve washed your products, i.e. use of a tumble dryer, iron, and if you’re really struggling – a hair dryer. Although, always look at the washing instructions on the label of your garment. Nikwax, on the other hand, say that you don’t need to use heat activation to enhance the reproofer and you can simply air dry your products.
Check out our range of cleaning and reproofing products here.
GORE – GORE-TEX®
A staple black GORE-TEX® diamond and arguably the most well-known waterproofing technology make for an iconic combination… at least in the world of waterproofing anyway. GORE have three main technologies under their waterproof wing, GORE-TEX®, GORE-TEX Pro and GORE-TEX® Active, all with slight differences in their properties to tailor the technology to whatever activity you may be doing.
Standard, but still exceptional - GORE-TEX®:
• Waterproof, windproof and breathable
• 4 breathability constructions available (varies dependant on product);
o 2-layer construction – membrane bonded to outer material, membrane protected on the inside by a drop lining o 3-layer construction – membrane bonded to outer material with a backer on the inside, forming a single fabric
o Z-liner construction – membrane is bonded to a lightweight fabric, newly formed ‘Z-liner’ is freely suspended between outer fabric and lining. This construction can also be used with insulation
o LTD construction – membrane is bonded to inner lining, the use of GORE-SEAM® tape ensures seams are fully waterproof also
Made for more extreme conditions, and more rugged for longer lasting performance - GORE-TEX® Pro:
• Extremely breathable, waterproof and windproof
• 3-layer construction - membrane bonded to outer material & specially developed inner lining
Designed for high-intensity pursuits and ultimate comfort - GORE-TEX® Active:
• Higher level of breathability than GORE-TEX® Pro and standard GORE-TEX®
• 3-layer construction with a thinner GORE-TEX® membrane attached to the backer textile, layered underneath a ≤40 denier outer fabric
View all GORE-TEX® products here.
The North Face – DryVent
What used to be known as HyVent, now DryVent from The North Face comes as either a 3, 2.5 or 2-layer construction. DryVent utilises a DWR coating on the outside of its products and a PU (polyurethane) coated fabric on the inside to bring ensure your product is waterproof, windproof and breathable. DryVent also features taped seams, taped seams give you added wet weather protection as rain can’t enter through holes left from stitching.
Ideal for extreme and technical uses - 3L DryVent:
• Intended for extreme use
• Ultra durable and breathable, designed for use in the most extreme of conditions
Lightweight and an ideal space saver – 2.5L DryVent:
• Perfect for high activity, fast and light pursuits
• Lightweight and packable
Ultimate versatility - 2L DryVent:
• Usually lined with another fabric for added warmth or comfort
• Can also be designed with fixed insulation for optimum warmth
View all DryVent products here.
Berghaus have developed an in-house range of technologies, utilising different properties to work to your advantage no matter the intensity of your outdoor pursuits.
Innovative Berghaus technology - AQTM2:
• Durable and high-performance waterproof and breathable technology
• Ideal for use in layering systems
View AQTM2 products here.
Constructed for versatility – Hydroshell:
• 2L construction
• ARGENTIUM® finish - to resist odours
• Fully waterproof and breathable yet extremely lightweight
• Intended for very high intensity activities
• 2.5L construction
• Lightweight and packable, with great breathability
Hydroshell Elite Pro
• The highest level of waterproofing among the Hydroshell range
• Breathability to match the standard Hydroshell Elite technology
View all Hydroshell products here.
With 35 years of experience, Pertex develop a weave of fine yarns to cater for a range of activities featuring different properties to suit your needs.
Lightweight and packable - Pertex Shield:
• Available in 2, 2.5 and 3-layer constructions and finished with a DWR coating
• Excellent windproofing properties
More superior - Pertex Shield Pro:
• Enhanced breathability and durability
• Ideal for prolonged use in extreme conditions
View all Pertex products here.
Jack Wolfskin - Texapore
Developed by Jack Wolfskin, Texapore has a number of different technologies under its umbrella, each with differing specialities to suit whatever you’re going to be using your product for.
The classic – Texapore:
• Fully windproof, waterproof and breathable
Greater breathability - Texapore O2+:
• Higher level of breathability
• Suitable for more active pursuits
A breath of fresh air - Texapore Air:
• Dynamic breathability - permanent air circulation that improves with movement
Exceptional breathability that keeps you dry - Texapore Infinity:
• The highest level of breathability among the Texapore technologies
• Remarkable waterproofing with a 20,000mm hydrostatic head
Exceptional gets better - Texapore Hyproof:
• Breathability of 35,000 g/m2/24h to match Texapore Infinity
• The highest level of waterproofing within the Texapore range
Protects you, and the environment – Texapore Ecosphere:
• Fully waterproof, windproof and breathable
• Membrane constructed from 100% recycled polyester with reduced CO2 emissions
• Lining made from 14 recycled PET bottles
• Completely PFC free
View all Texapore products here.
Columbia – Omni-TechTM
Tried and tested by Columbia, products using Omni-Tech technology are guaranteed to be both waterproof and breathable whilst keeping wind out.
View all Omni-TechTM products here.
Peter Storm – Storm Shield
Own brand technology from Peter Storm to keep you dry inside and out.
Defence against the Great British weather - Storm Shield:
• Waterproof and breathable, ideal for short adventures
Greater protection from the elements - Storm Shield+:
• Improved waterproofing protection
• Perfect for long hikes where rain is a risk
View all Storm Shield products here.
Although some technologies, i.e. GORE-TEX®, are renowned for their exceptional performance, it’s important when buying a new waterproof product that you take the end use into consideration. All products with a waterproofing technology will keep rain out and ensure a level of breathability, it’s important to think about the level of use you will get out of your jacket, what activities you will be using your jacket for, and how frequently you will be wearing it. If you’re using your jacket in extreme conditions and very frequently then investing in a GORE-TEX® product may be more beneficial, however if you’re using it to beat the elements through the office car park, a Peter Storm would be more than suitable.