sugar syrup

The following temperatures apply only to table sugar, the sugar that chemists call sucrose. Some sugars in fruit juices, for example, will caramelize at a much lower temperature.

Carmelization of sucrose begins at 335°F (168°C).

At higher altitudes, the stages occur at lower temperatures. For every 500 feet of altitude, subtract 1 degree from the Fahrenheit temperatures shown.

Designation Temperature
at sea level
On being dropped into ice water, it forms
in °F in °C
Pearl 220-222 104-106  
Thread 223–235 106–112 threads.
Blown or soufflé 230-235 110-112  
Soft ball 234–240 112–116 a ball that sags and flattens under its own weight.
Firm ball 242–248 116–120 a ball that holds its shape, but is easily flattened with the fingers.
Hard ball 250–268 121–129 a ball that holds its shape but is pliable.
Soft crack 270–290 132–143 hard but bendable threads.
Hard crack 300–310 149–154 hard, brittle threads.
Light caramel 320–338 160–170 turns brown.
Dark caramel 350–360 176–182 turns brown.

sources

Two 18th-century descriptions of the stages of syrup

1

161. Of the boiling of Sugar.

PEOPLE, for the most part, think Sugar is boil'd enough; when the Drops that are put upon a Plate grow thick, as it were a Jelly, and do not run; but tho' this Way of boiling may be sufficient for certain Jellies of Fruit and Composts, yet it is not enough in the whole Art of Confectioning. There are therefore neccessary to be known six Ways of boiling Sugar, that is, 'till it becomes smooth, pearled, blown, feathered, crack'd and caramel; and besides these, again are divided into the lesser and the greater smooth, the lesser and the greater pearl'd, feather'd a little, and a great deal, and so of the rest.

162. To boil Sugar to a Caramel.

If Sugar brought to the Quality commonly called crack'd, were put between the Teeth, it would stick to them as if it were Glue or Pitch; but when it is boild to its UtInoft caramel Height it will break and crack without sticking at all, therefore you must observe very diligently every moment; when it has attain'd to this last Degree of boiling, putting the foregoing Directions into Practice to know when it is crack'd, and afterwards biting the Sugar so ordered with your Teeth, to try whether it will stick to them or no; when you perceive that it does not stick to the Teeth, but on the contrary cracks and breaks clever, take it off the Fire immediately, or else it will be burnt, and fit for no Use at all.

But in Respect to the other well-condition'd Boilings, if after you have preserv'd any sweet Meats, some Sugar be left that is crack'd, or greatly feathered, and is of no further Use in that Condition, you need only put to it as much Water as will boil it over again, and then you may bring it to what Degree or Quality you please, and mix it with any other fort of Sugar or Syrup.

The pearl'd boiling of Sugar is generally used for all sorts of Comfits that are to be kept for a considerable time.

The caramel boiling of Sugar is proper for Barley Sugar, and for a certain small Sugar Work called by that Name, which is described in its proper Place.

163. The smooth boiling of Sugar.

You must first clarify your Sugar, and then set it on the Fire again, to boil it to its smooth Quality, and you may know when it is come to that, by dipping the Tip of your Fore-finger into it, and applying it to your Thumb and then opening them a little, for a small Thread or String will stick to both, which will immediately break, and remain in a Drop upon the Finger; when this String is scarcely to be perceiv'd, the Sugar has only boil'd 'till it is a little smooth; but when it extends it self further before it breaks, then the Sugar is very smooth.

164. To boil Sugar to its blown Quality.

WHEN the Sugar at its pearled Quality has boiled a few more Walms*, shake the Skimmer a little with your Hand, beat in the Side of the Pan, and blow through the Holes of it, and if certain Sparks, as it were, or small Bubbles, fly out, the Sugar is come to the Degree or Quality called blown.

165. To Clarify Sugar.

PROVIDE an earthen Pan of a size proportionable to the Quantity of Sugar you would clarify, put in it a little Water, and break into it an Egg, or more, according to the Quantity of Sugar, put in Shell and all; then Whip up the Egg with a Whisk or Birchen Rods, and pour it upon your Sugar that is to be clarified; then set it over the Fire, and keep it continually stirring ; when it boils scum it well; and as the Sugar runs from time to time, put in a little cold Water to hinder it from running over, and also to make the Scum rise the better; and add also the Froth of the White of an Egg whipt apart: when you have scumm'd the Sugar thoroughly, so that there only remains a small whitish Froth, not black and foul as before; and that the Sugar being laid upon the Skimmer or Spatula, appears very clear, take it off the Fire, and strain it through a Straining-bag, as your Sugar will be compleatly clarified.

166. Another Way.

FIRST dissolve your Sugar in Water, put into it the White of a whipt Egg, set it on the Fire, and when it swells up, and is ready to run over, pour on a little cold Water to check it; but when it rises a second time, take it off the Fire, and set it by for about a quarter of an Hour, and the Sugar will sink, leaving a black Scum on the top; take this off gently with the Skimmer, and it will be sufficiently clarified, tho' not quite so clear nor white as that clarified the former Way.

167. To boil Sugar to its crack'd Quality.

To know when the Sugar has attain'd to this Degree, you must provide a Pot or Pan with some cold Water: Dip the tip of your Finger into it, then dip it quick into the boiling Sugar, and then immediately into the cold Water; and keeping your Finger in the Water, rub off the Sugar with the other two Fingers; and if it breaks afterwards, making a kind of crackling Noise, it has attain'd the crack'd Quality.

168. To boil Sugar to its feather'd Quality.

WHEN after some other Boilings, you blow through the Skimmer, or shake the Spatula with a back stroke 'till thicker and larger Bubbles rise up on high, then the Sugar has attain'd its feather'd Quality; and when, after several Trials, you perceive the Bubbles thicker, and in greater Quantity, so that several of them stick together, and form, as it were a flying Flake, then the Sugar is greatly feather'd.

169. To boil Sugar to its pearl'd Quality.

HAVING boil'd your Sugar to its smooth'd Quality, continue the boiling a little longer, and then try a Drop of it between your Finger and Thumb, as before, and if the String continues flicking to both, the Sugar is arriv'd at its pearl'd Quality; the greater pearl'd boiling is when the String remains, tho' the Finger and Thumb be quite stretch'd as far as you can extend them asunder; this Degree of boiling may also be known by a sort of round Pearls that rise on the Top of the Sugar.

John Nott.
The Cook's and Confectioner's Dictionary, or, the Accomplish'd Housewife's Companion.
London: Printed for C. Rivington, at the Bible and Crown, in St. Paul's Church-yard, 1723.

* Walm: “A spell of boiling” (Oxford English Dictionary). But see the OED entry for the related meanings of this very interesting old word.

2

To boil Sugar to the degree called smooth.

When your sugar is thus clarified, put what quantity you have occasion for over the fire, to boil smooth; which you may prove by dipping your scummer into the sugar, and then touching it with your fore-finger and thumb; in opening them, you will see a small thread drawn betwixt, which immediately breaks, and remains in a drop on your thumb; thus it is a little smooth—when boiling more, it will draw into a larger string, and become very smooth.

The blown Sugar.

Boil your sugar longer than the former, and try it thus:—dip in your scummer, and take it out, shaking off what sugar you can into the pan, and then blow with your mouth strongly through the holes; and if certain bubbles or bladders blow through, it is boiled to the degree called blown.

The feathered Sugar.

It is a higher degree of boiling sugar; which is to be proved by dipping the scummer, when it has boiled a little longer; shake it first over the pan; then give it a sudden flurt behind you; if it be enough, the sugar will fly off like feathers.

The crackled Sugar.

Is proved by 1etting it boil rather longer; and then dipping a stick into the sugar, which immediately remove into a pot of cold water, standing by for that purpose, drawing off the sugar that cleaves to the stick; if it becomes hard, and snaps in the water, it is enough; if not, you must boil it till it comes to that degree.

Note.—Your water must, be always very cold, or it will deceive you.

The carmel Sugar.

Is known by boiling yet longer; and is proved by dipping a stick, as aforesaid, first in the sugar, and then in the water; but you must observe, when it comes to the carmel height, it will snap like glass the moment it touches the cold water, which is the highest and last degree of boiling sugar.

Note.—Observe that your fire be not very fierce when you boil this, lest flaming up the sides of your pan, it should cause the sugar to burn, and so discolour it.

H[annah] Glass, with additions and corrections by Maria Wilson.
The Complete Confectioner; or, Housekeeper's Guide: To a simple and speedy Method of understanding the whole art of confectionary; etc
London: West and Hughes, 1800.
Pages 2 & 3.

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