Why breathability depends upon water repellency:

Breathable waterproof garments are most likely to get sweaty and wet inside when used in damp or wet conditions. If the outer fabric absorbs water, the garment can lose up to 70% of its breathability. Therefore, the Durable Water Repellency (DWR) on the outer fabric of your jacket must be maintained to ensure comfort. It will eventually wear off and need to be renewed with Nikwax TX.Direct®. 

When we work hard, we sweat. The evaporation of sweat cools us down and keeps us comfortable. But, when it rains we want to avoid getting wet, so we put on waterproof outerwear to keep us dry.
The waterproof fabric must allow moisture vapour to pass through it, or 'breathe'; otherwise our sweat cannot evaporate, causing us to overheat and get wet from condensation. Additionally, if the outer fabric of your garment absorbs water and ‘wets out’ its breathability will be reduced, causing you to feel clammy and wet.
Nikwax TX.Direct® adds Durable Water Repellency (DWR), which prevents water absorption, whilst maintaining breathability, keeping you dry and comfortable. Anyone who is active outside in damp or wet conditions will benefit from breathable waterproof clothing. Whether you’re a mountaineer, cyclist, dog walker, or you work outside as a farmer or surveyor, you will need good raingear. 

How Nikwax TX. Direct® Spray-on protects:

Nikwax TX.Direct® Spray-On is easy and quick to apply, and its highly Durable Water Repellency (DWR) develops on air drying. The need for tumble drying is removed, this saves energy and protects more vulnerable, older, garments from heat. Nikwax TX.Direct® Spray-On has been specifically designed and optimized for breathable waterproof garments; it leaves a flexible water repellent treatment on individual fibres allowing moisture vapour to pass through, maintaining breathability.
The spray-on application allows for direct treatment of areas which require it most (e.g. elbows and seams on jackets) and will not compromise the properties of internal wicking liners.

Like all Nikwax products, Nikwax TX.Direct® is safe to use:

Nikwax takes great care to minimize the effect of Nikwax products on the environment and on you, the consumer. Nikwax waterproofing products are WaterBased, non-aerosol, non-flammable, non-hazardous and environmentally friendly. They contain no harmful solvents or volatile organic compounds (VOCs), and are completely free of fluorocarbons (which have been shown to be persistent in the environment and have been associated with serious health issues). 

Apply Nikwax TX.Direct® Spray-On by hand:

For best results remove all non-washable parts and always clean item(s) first with Nikwax Tech Wash®. No need to dry item(s) before waterproofing.

• Protect working surface and lay clean garment flat and zip up all zippers.
• Hold bottle 15 cm/6 inches away from garment.
• Apply evenly to outside of fabric.
• Wait for 2 minutes. Remove any surplus product with a damp cloth.
• Check carefully to ensure no areas have been missed.
• After several minutes check for and remove any surplus product with a damp cloth.

Nikwax TX.Direct® treated cklothing needs no heat to develoop Durable Water Repellency (DWR):

Air dry or tumble dry on a low setting if care label allows.