Milk watcher

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Instructions for use of a Milk Saver
Porcelain Milk Watcher - Notice that there is one notch on each side, and how the interior slants toward the notch
Glass Milk Watcher
Stainless Steel Milk Watcher

A milk watcher, milk saver, pot watcher, pot minder, milk guard, or boil over preventer is a cooking utensil placed at the bottom of a pot to prevent boiling over of liquids, and especially the burning (scorching) of milk.

A milk watcher is a disk with a raised rim, and is notched on one side (see images). Some milk savers are designed so they can be used with the obverse or reverse side facing up, so they appear to have two notches. The interior of the disk is not level; it slants upward toward the notched side creating a space just behind the notch where water vapor can collect. Water vapor is trapped under the Milk Saver causing the notched side to rise up, releasing the water vapor at the same time circulating liquid around the base of the pot and making a rattling noise.[1]


The milk watcher was invented by Vincent Hartley in 1938.[2]

How it works[edit]

Normally, boiling water does not boil over. When fats, starches, and some other substances are present in boiling water, for example by adding milk or pasta, boiling over can occur. A film forms on the surface of the boiling liquid; for example, cream can boil over as milk fat separates from the milk.[3] The increased viscosity of the liquid causes the steam bubbles to form foam trapped under the film, pushing the film up and over the lip of the pot, boiling over. A milk watcher disrupts this process by collecting small bubbles of steam into one large bubble and releasing it in a manner which may puncture the surface film. The device also rattles when boiling occurs, alerting the cook who may then lower the heat setting of the stove.

By circulating fluid around the bottom of the pot the device may also prevent material from being deposited and eventually burned on the pot's bottom.[4]


  1. ^ Image:Solidex Package Back.JPG Reverse side of Solidex Milk Saver packaging
  2. ^ History of Hartley Botanic
  3. ^ "Why does Milk spill over when it Boils?". Archived from the original on May 4, 2008. Retrieved 2009-03-19.CS1 maint: BOT: original-url status unknown (link)
  4. ^ What is Scorching or Scalding Milk?

External links[edit]

Media related to Milk watcher at Wikimedia Commons