For many months now I have delved over the decision to treat my new Feet-Paws with Scotch-Guard or not after hearing such a mixed bag of yea's and nay's.
I decided to start on the safe side and have sprayed test swatches of faux fur that I used on my new Paws to see for myself the issues it may cause. Now, the actual version of the spray that you want is not all that big a deal to decide on... the ingredients are pretty much the same in all of them for the most part but after reading through each products write-up on the 3M website I chose the Heavy Duty Water Shield because of one simple line that says "Safe for use on polyester, nylon, polypropylene, cotton, leather, suede and more... "
Which ever version of the product you choose to use it is recommended to try the product first on an unseen area or as most do an unused swatch of fur first to make sure of the color fastness and to see if any other unwanted affects develop. You most definitely want to use this product outdoors weather permitting or at least in an area that can be closed off from the rest of the house with an open window, fumes are terrible if you are sensitive to such things.
I sprayed down these two test pieces of fur last evening in my woodshed, combed them out and left them there to dry over night. This morning after brushing them again the fur has returned to its normal texture. The Grey fur however has more of a sheen or sparkly appearance now, the darker fabric has more contrast to the coating thus it can be seen as a glittery reflection in the light. I personally don't find this of any concern because I value the protection this product will give in terms of repelling stains, I am only spraying it on the Feet-Paws anyway. I was concerned about the odor from the Scotch Guard but as the test swatches have dried and warmed up the odor has dissipated, after a day or two airing out it will not be an issue. Just be sure that any time you want to retreat the areas (and it is recommended that you do) to do it well in advance of when you need them so they have time to "air-out".