Gore-tex recommends the following (see http://www.gore-tex.com and click on "care center"):
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WASH
Machine-wash warm (104° F/40° C). Powder or liquid detergent. No fabric softener. Follow manufacturer's instructions.
DRY CLEAN
If professionally dry-cleaned, request clear distilled solvent rinse and spray repellent. Follow manufacturer's instructions.
IRON
Steam-iron warm, placing a towel or cloth between the garment and the iron. No need to iron the garment until it is completely dry.
BLEACH
No chlorine bleach. It may damage your garment.
DRY
Tumble-dry warm. The heat from the dryer will help to reactivate the durable water repellent (DWR) treatment on your garment's outer fabric.
WATER REPELLENT TREATMENT
Gore recommends applying a topical water repellency restorative (DWR treatment) for outdoor fabrics, available at your local outdoor retailer. We do not recommend wash-in treatments as they can affect the garment's breathability.
STAIN REMOVAL
Use a pre-wash treatment such as Shout® or Spray 'n Wash®, following its manufacturer's instructions. Rinse well.
Restoring Water Repellency
“Wet out” can put a real damper on your day. That’s when liquid saturates your garment’s outer fabric layer above the GORE-TEX® membrane, leaving you feeling damp and clammy – as if your garment were leaking, even when it’s not.
To prevent wet out, all GORE-TEX® shell fabrics are treated with an ultra-thin treatment called DWR, a durable water repellent polymer that is applied to the outermost fabric layer. DWR penetrates the fibers and lowers the surface tension of the fabric, causing water to bead up and roll off this outer layer of fabric, instead of being absorbed.
DWR is not permanent, though. Regular wear and tear, plus exposure to dirt, detergents, insect repellent, and other impurities can shorten its lifespan. The good news is that restoring the water repellency of your GORE-TEX® shell is extremely easy.
How to Restore Water Repellency
GORE-TEX® outerwear:
Just machine wash it, rinse it, and put it in the dryer, being sure to follow the manufacturer’s instructions on the care label inside. The washing removes dirt and other contaminants and the heat from the dryer helps redistribute the DWR treatment on the fabric surface.
If water fails to bead up on the surface of your cleaned and tumble-dried garment, its DWR treatment has reached the end of its useful life. But don’t worry: You can restore the garment’s water repellency by applying a topical water repellency restorative (DWR treatment) for outdoor fabrics, available at your local outdoor retailer. We do not recommend wash-in treatments, as they can hinder your garment's breathability.
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I have used Tech Wash and it seemed to be a good product, but from everything I could see, it was just a good liquid detergent. No science in this, but just judging by y skin contact with the stuff. The main action in detergents is to cut oils and release those soils held in place by them. Water does the rest. I guess you could try a few drops of dilute detergent (as it would be used) on some oil in water and see how it disperses the oil compared to a working solution of your favorite laundry detergent. Gore's recommendation that products like Shout can be used tells me that detergent won't destroy their DWR in one pass, as Shout and similar products are just concentrated detergent.
My estimation of all this is to wash these garments gently, rinse them well and follow the drying instructions carefully. As you can see from Gore's instructions, heat reactivates the DWR. This has been the case for many years. I htink Tech Wash is a bit of truth and a bit of hype.