Some types of it are sold already cooked, and able to thicken food instantly without the usual cooking needed with starch. It can be added to hot or cold liquids. If liquids are cold, it will reach its maximum thickness in 10 minutes.
Products made with it survive freezing well.
Clearjel is a modified starch made from corn. It contains amylo pectin, but is less expensive than commercial pectin
It is used as a stabilizer in foods such as pies, particularly in commercial pie baking and in place of corn starch in fruit pie fillings. It can also be used in preserves such as jams and jellies and fruit butters, in place of pectin.
It is currently (2014) the only thickener approved for use in home canning (aka bottling) by the American National Center for Home Food Preservation.
There are several different types:
- Clearjel A: (Also referred to as “regular” or “cook type” Clearjel. This is sold not already cooked, and needs to be cooked. Dissolve first in cold water. Use for pie fillings, sauces, gravies. This is the Clearjel to use if you are planning to use it for home canning. The USDA has released several recipes for home canned pie fillings thickened with Clearjel;
- Ultra Maxi Gel: This is sold already cooked. No cooking is needed. It reaches full set in 5 minutes. It is best in foods that aren’t going to be cooked. Use for freezer jams, syrups, pie fillings, custard-type puddings
- Instant Clearjel: This is sold already cooked, and reaches its full set in 10 minutes. No cooking is needed. It is best in foods that aren’t going to be cooked. When using, reduce sugar in the recipe by half. It can be used to thicken freezer jams, custard-type puddings, pie fillings, syrups, toppings, pie glazes, drinks, etc. Do not use in canning; use the regular in canning.
Per 4 cups of fruit, use 1/3 cup plus 2 tablespoons of Clearjel.
When whipping whipped cream, a few teaspoons of Instant Clearjel can increase the stability life of your whipped cream. This will allow you to pipe the whipped cream onto pies, etc, earlier, rather than at the last minute, and the whipped cream will stay whipped for 3 to 5 days in the fridge. The ratio to use is 1 to 2 teaspoons per 500 ml (16 oz / 2 cups) of cream to be whipped.1
There are alternatives recognized as safe by some University Extension offices in the States: Thick Gel, recognized by Utah Extension, and ThermFlo recognized by Pennsylvania State University. 
1 tablespoon = 4 grams
1 pound Clearjel = 3 cups Clearjel
1 tablespoon cornstarch = 1 1/2 tablespoon Instant Clearjel
2 tablespoon flour or tapioca= 1 tablespoon Instant Clearjel
Store indefinitely in sealed container.
Clearjel has been sold since about the 1970s. It is very popular in Amish cooking.
It’s as difficult to find the correct spelling of Clearjel as it is the product itself: you will see Clear Jel, ClearJel, etc. The maker (Ingredion) and all filings at the US patent office referencing the product use the spelling of Clearjel®. Consequently, we have opted to go with that.
You usually can’t go by the spelling on the packages, as it’s almost always re-packaged into smaller packages by third-party vendors, who spell Clearjel however seems best to them.
 “ThermFlo is an acceptable alternative to use in canned pie fillings because it is also stable during heating and exhibits about the same viscosity during heating as regular Clearjel . It also has the added advantage of holding up well during storage.” Penn State Extension. Modified Food Starches. 12 October 2012. Accessed December 2014 http://extension.psu.edu/food/preservation/news/2012/modified-food-starches
“Well, solving the problem of fallen whipped cream is one of the easiest uses ever of E-Z Gel [Ed: E-Z Gel is an equivalent product to Instant Clearjel]. When I whip my cream I add 1-2 teaspoons of E-Z Gel to the mix. This addition of starch helps to stabilize the whipped cream and makes it possible to pipe whipped cream on pies early with beautiful results. As well the whipped cream stays good in the fridge for an additional 3-5 days. I can attest to this because it’s currently Tuesday and I’m still eating the pumpkin cake and whipped cream I whipped on Saturday! Admittedly, the cream isn’t quite as pretty after a few days in the fridge, but it’s still light and airy, sweet and rich…perfect.” Cornaby, Dave. E-Z Gel Whipped Cream. 28 November 2017. Blog entry at https://cornabys.com/e-z-gel-whipped-cream/ ↩