My first attempt failed today trying to make marshmallow fondant. It's about 85% humid here in TX today. Will that affect it? I followed the directions to a T but in the end it was very dry, then sticky, then I was trying to compensate with some water, then I think perhaps I used too much crisco since it kept sticking to the counter and then it was a just greaseball, haha. I just need it for 2D cutouts for the side of my son's cake this weekend and wanted to make and color it today to let it set up and color it in advance. I'm doing an owl theme and just need a few cute things and I plan to buttercreme a 3 layer cake , then use a chocolate ganash over it for the shine. Any more issues I can forsee? Thanks so much!

After making the mmf you have to let it "rest" for several hours before you can work with it. High humidity can effect the outcome, but can usually be compensated for. In my experience it is better to add corn syrup than water to help get the right consistency. Here is the recipe that I use and have never had it fail.

Ingredients
16 oz of mini marshmallows (a good brand works best)
2 tbs water
1 tsp vanilla  
3 tbs butter, softened, but not melted (not margarine, can be omitted)
2 lbs powdered sugar

Instructions
  Melt Marshmallows, water, and vanilla in a large bowl in microwave.
  Stir until all is combined and marshmallows are smooth.
  Add butter and stir again.
  Add 2/3 of the powder sugar and mix with a spoon as long as you can.
  When it gets too hard to stir coat your hands with crisco and knead the rest of the powdered sugar into the ball.
  When all the powdered sugar is combined, roll it into a ball and put it in 2 ziploc bags. Let it rest for 24 hours.
  Color and use as you like!

Sorry, double post!

Please note, it may not take all the PS. I have yet to add a full 2lbs of PS to my MMF. But with the high humidity you may. Also, I agree, use corn syrup not water if you need to loosen it up.

Usually I kneed in the PS unitl it seems like it just won't take any more then form a ball and coat the entire thing with a very thin layer of shortning and double wrap with plastic wrap and put it in the cabinet over night and check it the next day. If it is really sticky, I'll add more PS until no longer sticky but still pliable and add color. Just remember, the color is a liquid so you may need to add additional PS to compensate when coloring a deep color.

One last tip, if when you go to use it it is too stiff, give it 5-10 seconds on med in the microwave to soften it up a bit. It softens from the middle and inside out (in my microwave anyway) and gets lava hot fast so use short bursts of time.

I live in Indiana where our summers are very humid therefore, I have had to add the full 2lb. of PS, but in the winter I don't. Just depends on the type of day. Also, as with anything, once you work with something a few times, you kind of get the "feel" for it. My first few attempts at MMF bombed too.

I have actually begun using my MMF right after I make it. I got tired of having to soften it in the micro, and then knead like crazy to get the texture perfect again. I've been making and using it right away for a couple of months now and I love it.

Do NOT add water! You don't even have to add it to the marshmallows prior to microwaving, but I do sprinkle them with a few drops. Especially when it's humid - the water just adds to the stickiness.

I add a tablespoon of glycerine after the MM's are melted, along with the flavoring and color (Michaels and Joann's carry Wilton glycerine, or you can buy larger bottles of CK brand online). You can substitute corn syrup for the glycerine, but the end result isn't as great.

To re-use left-over MMF, nuke it a few seconds. Be careful, small amounts can melt quickly.

And yes, in humid weather or when adding a lot of color, use the full 2lbs.

Tip: For red or black, use a full 9oz jar of powdered food color together with Wiltons red-red or black (Wilton's are not as liquid as Americolor, so they work better).