Yes, to ensure Granger's 2in1 is effective, heat is essential to complete proofing.
If you cannot get access to a tumble dryer, use Granger's separate wash-in 30°C Cleaner & 30°C Proofer. You must always follow the garments care instructions, these supersede any instructions on the Grangers Products. Grangers make a number of products which do not require tumble drying.

All Granger's wash-in products will work at temperatures as low as 30°C. You can use a cool setting or your normal setting. Always check your garment care label for the recommended heat setting. The advantage of using a low heat setting like 30°C is that it will save up to 40% in electricity.

It is not essential to dry between washing and proofing.

Yes, without a doubt. Granger's products are water-based and use the same fluorocarbon technology as fabric manufacturers. Independent tests have shown they do not contain any harmful compounds.

Soft shell fabric technologies also rely on DWR (durable water repellency) treatments to keep water out, and exactly the same advice applies. Maintaining water repellency is often more essential than with hard shell garments. Hard shells usually keep exterior water out even when the DWR is worn out, whereas soft shells really need to retain their water repellency to keep you dry. Apply Granger's re-proofing products the minute you find that washing is not enough to maintain water beading on the outside. Beading indicates varying levels of a garments water repellency or waterproofness. No beading indicates the garment is not water repellent at all.

Again, this depends on the proofing product and garment usage. Granger's proofing technologies replicate the DWR formulation originally applied by fabric manufacturers, so this effectively just restores the original treatment. Logically this should help the garment to retain a longer life of full water repellency.

For further information please visit: http://www.grangers.co.uk/FAQ.cfm