I don't know anything about McDonalds resin,just their burgers.
Seriously though I prefer to use resin from reputable sources that deal with the marine trade,not a resin from a hardware store or big box store.It's not to say that it's no good,but Polyester resin does have a shelf life,and much of it in hardware stores has been sitting around for a long time.
There are also poor quality and high quality polyester resins.Don't skimp on the quality.
POLYESTER RESIN IS FINE FOR THE JOB YOU'RE DOING, but use a good quality product,it will cost a bit more but it will be stronger and easier to wet out the fabric with it.
Use a glass supplier near you that specializes in marine glass and resin.There are several that guys on this site can recommend to you.
I've always used stuff from Merton fiberglass supply and have never had a problem.He ships everywhere and quick.I'm sure others on the site have their favorites as well and can recommend them.
This is the link to Mertons
www.mertons.com