Most nylon string guitars come without a pickguard and my play tends to scratch the finish. I've been using the .005 clear mylar for about 10 years and think it's a great product. I'm now using the mylar on my carbon fiber guitars and it works well. This pickguard material protects the finish of the guitar, it can hardly be seen and it allows the beauty of the instrument to show.
I've had issues with this material and instructions, which I don't think are specific enough. The dry install does provide good enough quality. Wet install is difficult on some finishes due to beading, and have to use more wetting agent than suggested. There is also a purplish streaking on the material, and it does not lay flat. I have suggested to Stew-Mac that they consider selling instead the same material used on cell phone screen covers, which I think would work better, if they can get sheets large enough.
Tried this out for the first time recently when I was fitting a golpeador for a customer. The material cut cleanly and easily and was of sufficient thickness to provide good protection. I fitted it using the water method. This made the job easy beyond belief and gave impeccable results.. not a blister in sight! Thoroughly recommend.
This stuff has been great, not only for putting pick-guards and golpeadora on guitars, but I've also used it to fit pick guards to a variety of more 'exotic' axes: cuatro; li'liu; bajo sexto; tiple -- not to mention ukes. I do recommend that you get a 2-4" medium rubber roller (can be had from an art or printers' supply shop) and use it to firmly seat the material while rolling out any air bubbles. And use -sharp- scissors to get a clean edge. Other than that, easy to work with, durable, and next to invisible when properly applied. All I'd like now is to see it come in a couple of different thicknesses.
These mylar sheets cut easily, adhere very well and provide a tough protective layer that almost disappears. Worked out great on a classical for flamenco style playing. The four sheets will make large pick guards for at least eight guitars, maybe more.