Marshmallow Making Tips

In a moment of... something... I decided to make fancy marshmallows for my entire department as a holiday gift.  (There are 24 people in this department.) Here I have collected all the things I learned from the internet and/or painful experience.

Figure 1: Supplies for Less Sticky Marshmallow Making

1. This recipe is mostly fine and this one is extremely detailed.  (I am trying coffee marshmallows next!) Use a recipe that calls for a thermometer and boil the sugar to 240F.
2. Use cooking spray, not oil (the silicone helps maybe?  I don't know.)
3. Spray your marshmallow-forming tray or dish, then wipe it with a paper towel so it's evenly coated.
4. After your marshmallows have set, take a piece of parchment paper and spray it too, then wipe with a paper towel.
5. In a bowl, mix about 1:3 cornstarch and powdered sugar.  I used one cup of powdered sugar and it was enough for four batches of marshmallows.
6. Spray and wipe a knife and kitchen scissors.  Cut strips with the kitchen scissors, then transfer the strips to the parchment paper.  Cut them into squares with the knife.  Roll in the sugar/starch mixture and store in something (here I have a Ziploc bag).
7. Re-wipe the knife and scissors regularly.
8. If you run out of corn syrup part way through, use the equivalent mass of sugar (about 3/4 cup white sugar per cup corn syrup) and add a teaspoon of lemon juice* and simmer to temperature more slowly.
9. Add the salt to the gelatin bloom.
10. You can add the flavoring after the mixture is stiff, but it doesn't always mix in well (see also: some marshmallows which are VERY PEPPERMINT right now).  You can add it to the sugar syrup, but your marshmallows will be slightly flatter, especially depending on the oil content of the extract.**  If you add it at the very end, make sure to stir well with a spatula.
11. I have only succeeded in smoothing the surface by putting a well-oiled parchment paper on top.  Spatulas resulted in sticky mess everywhere.

Happy marshmallow making!

Updates:
 1. We have lost the pizza wheel so I have no data.
2. Chilling does make them easier to cut!
3. I made the Bravetart  marshmallows with exactly four drops liquid smoke (and a little butter vanilla flavoring) and they are the best marshmallows I have ever eaten (warm: when cooled they were not smoky enough, rats.)
4. If you're going to drizzle with chocolate don't roll in powdered sugar first. It doesn't stick.

Finished product:

* You get acid-catalyzed hydrolysis of the sucrose, which prevents crystallization because you have a mixed system then.

** Oil tends to destabilize water-protein emulsions.