There are many terms used on rainwear labels, such as “waterproof,” “water resistant,” and “water repellent,” but in this context, “waterproof” simply means that the rainwear fabric does not allow water (rain) to pass through it.
We not only use waterproof fabric but also seal off all seams of our garments with seam tape, extending waterproofing to the seams as well.
“Water repellent” means that the outer surface of the fabric repels water (rain). Unlike waterproof fabrics, water repellent textiles prevent seepage into the fabric’s surface. If water repellency decreases, maintenance is required.
This refers to the breathability of the fabric, i.e. the ability of the fabric to allow water vapor (sweat) to be released through the garment. This is often used with waterproof fabric. The higher the moisture permeability value, the less likely a garment is to feel clammy.
GORE-TEX fabric (ePTFE)
GORE-TEX has extremely high waterproof, moisture permeability, and durability characteristics, and is also wind resistant. It is a leading waterproof yet moisture permeable fabric. Machine-washing and dry cleaning is possible in most cases; please read the care label carefully. Water repellency can be restored by removing the dirt and drying it, but maintenance is required when the water repellent on the fabric surface runs out. This material is resistant to aging and can be used for a long time.
PU (polyurethane) fabric
PU fabrics are highly waterproof and moisture permeable and are available at an accessible price.
Use of a washing machine and dry cleaning however are not possible in many cases, therefore requiring hand washing. The moisture permeability functions vary significantly by product.
PVC (polyvinyl chloride) fabric
This fabric has high waterproof functionality. Many PVC fabrics have excellent durability and cost-performance ratios and are used in everyday rainwear.
As PVC fabrics have no moisture permeability at all, they are suited to being worn for a short time only.
Garments whose waterproofing has become ineffective refers to the following situations.
– The waterproof membrane on the fabric inner surface has degraded, and holes have appeared in it
– The waterproof sealing tape applied to the seam backing has degraded, and water is seeping through the seams
While there are variations depending on the type of waterproof membrane (PVC, PU, PTFE), sealing technology, and how the product is used, as an approximate guide PTFE (GORE-TEX) will last 5-10 years, PVC 3-5 years, and PU 2-3 years.
The water pressure resistance value indicates the ability to withstand the force of water trying to seep into the fabric.
Imagine that a column of water 1cm square was placed on top of the fabric. The value indicates resistance to the water pressure, measured by the column height up to which the fabric does not allow seepage. A value of 10,000mm means that the fabric can withstand the force of water from a column 10m high.
Expressing water pressure resistance values in terms of amounts of rain is problematic, but in general, it is considered that heavy rain would be 10,000mm and a storm 20,000mm or more. Thus, we can say that a product with water pressure resistance of at least 10,000mm is likely to be sufficient for everyday usage. If you may be working in the rain for an extended period, we recommend rainwear with performance of at least 20,000mm.
Does this mean that the fabric has degraded?
After wearing a raincoat for a certain length of time, condensation buildup means it will naturally become damp inside and does not necessarily mean that the fabric has degraded. Some raincoats have ventilation installed and/or use fabric with high moisture permeability to help mitigate the effects of condensation buildup.
Regardless of the type of material, regular care can make the waterproofing last longer.
Please refer to “Caring for your MAEGAKI garment”