I found a recipe for a gelatin desert I'd like to try. But there was one step I don't feel prepared to tackle:

In the meantime, in a small sauce pan heat ¼ cup of water to about 100 degrees. Add the gelatin to the water and let dissolve.

I don't have a candy thermometer to measure the temperature of my water. Would it be sufficient to use hot tap water? Or should I bring the water to a slow or full boil? Does the precise temperature make a difference when dissolving gelatin or is it ok to be rather approximate?

  • 2
    Would you please clarify: Are we talking about 100 degrees Celsius or Farenheit? I assume it's Farenheit, but as you are talking about boiling...
    – Stephie
    Sep 12, 2015 at 18:56
  • 3
    Assuming this means 100° Fahrenheit -- 100°C is easy -- full boil! But I don't think you'll want boiling water for gelatin. 100°F is hotter than normal tap water, and you might prefer filtered water. What's the application? Comfortably warm is ~110°F / 45°C, which is common for yeast (active dry / instant) breads, if you're a baker. Candy thermometer might not read as low as 100°F anyway.
    – hoc_age
    Sep 12, 2015 at 18:57
  • 1
    Hoc said it presicly how it is. Full boil. Easy .
    – Pork Chop
    Sep 12, 2015 at 21:47
  • 1
    Is this sheet or powdered gelatin? I ask because there's typically a hydration step (aka 'blooming') -- for sheet gelatin you soak it in cold water before adding it to the hot liquid. For powdered, you'll add it to some cold liquid, let it sit and become a blob, then add it to the hot liquid. It's possible that there was a blooming step that came before this.
    – Joe
    Sep 14, 2015 at 17:22
  • 4
    since Jessica hasn't edited it yet and everybody's guessing wildly, I just put Fahrenheit in. If your recipe tells you to use 100 C for gelatine soaking, find another recipe!
    – rumtscho
    Sep 14, 2015 at 19:54

3 Answers 3


Gelatin is quite tolerant, but with a few restrictions:

  • Never boil gelatine, because it looses it's binding/gelling properties.
  • Liquifying gelatine requires temperatures that feel "warm" to the touch, but not all recipes handle warm additions well - e.g. whipped cream.
  • Cooling liquid gelatine for heat sensitive recipes should happen fairly quick, and so should incorporating the coolish gelatine to the other ingredients : Stir well or you end up with "gummy bear"- like lumps.

So without knowing the details of your recipe I suggest using fairly warm water in the range of "warm bath water" or "comfortable for washing hands" but not at all "hot". (Note that I don't give a precise temperature range on purpose.) Hot tap water should suffice, but heating it on the stove is fine, too. Just use gentle heat and don't let the gelatine rest on the bottom of the pot to avoid overheating. Depending on your next steps, you might want to stir the liquid gelatine until it's barely warm to the touch or add a few spoonfulls of whatever cool mixture you are planning to bind, stir, then add to the rest. For warm other ingredients, extra cooling is not required, just mix and let set.


You are not specifying whether it's 100 degrees Celsius or Farenheit.

If it's Celsius, 100°C is the temperature of boiling water (at sea level). Just full boil it.

If it's Farenheit, 100°F is very close to body temperature (if you're not ill). You can use a normal medical thermometer.

  • The recipe didn't specify whether it was Celcius or Farehnheit either ;-). Since the rest of the units were imperial, I'm going to presume it's referring to Farenheit. Sep 15, 2015 at 17:47

Besides the usual measuring cups and a tongue for licking the cake batter bowel, you should have a digital scale and a thermometer as standard "kit" (as the Brits would say). You don't need a high temp candy thermometer for most cooking. There are some thermometers that you can put in the oven and some that you can't...they will literally melt.

You need a general thermometer for food safety. I recommend a probe thermometer.

In a pinch, if you have a window thermometer, the glass bulb kind, you might be able to clean it up a bit and use that. The newer ones don't contain mercury. They have alcohol with a dye. So I would consider it safe to use.

Likewise, if you have a medical thermometer in your medicine chest, the 98.6 thermometers used for humans is in the ballpark of the 100F degrees you're looking for. A digital medical thermometer would be even better as they give you an accurate reading in a split second.

  • This doesn't answer the question about when you can melt gelatin if you don't have a tool to measure temperature. It's a useful comment though.
    – Erica
    Sep 17, 2015 at 11:11
  • Actually, the question, as asked, is how to tell when water reaches 100 degrees. The gelatin part is irrelevant with regard to determining temp. As a reference, a properly set water heater will have a nominal hot water temp of 125F, 120 if there are small children in the house.
    – user36802
    Sep 17, 2015 at 13:28
  • See, THAT is good information :) I may not have time to run out and buy a candy or probe thermometer when I'm about to melt gelatin, but knowing an approximate reference is really helpful.
    – Erica
    Sep 17, 2015 at 13:33
  • I have to add a couple caveats. The key words are "properly set". Many people crank up their water heaters which can lead to scalding and premature water heater failure. Also the temp will cycle up and down for efficiency. Sometimes the water will be hotter than the nominal setting, sometimes lower. Back to square one, to know where your heater is set...you need a thermometer.
    – user36802
    Sep 17, 2015 at 13:38
  • Updated to better answer the question.
    – user36802
    Sep 17, 2015 at 13:51

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