When you work with royal icing everything has to be grease free. You have to clean all your tips, spatulas, bowls etc. I use vinegar to de-grease everything. You cannot do that to anything plastic like tupperware or cloth bags. I used to use a separate plastic bag each time. Gets to be a little expensive. I have learned a new trick for piping royal icing. Karen has a great short video on how to do it: karens cookies
I was in love with it the first time I tried it! Will never go back.
Lay a sheet of saran wrap on your counter. Drop some icing in the middle.
Fold the corners together the triangle way. Roll it up.
Then do a hard roll, like a wet towel. Just don't try to smack anyone in the butt with this :)
Thanks for looking!