M.C. Miller, Gen II Leak Stop Gel, Anti-Freeze

Gen II Leak Stop Gel creates Semi-Permanent Electrodes

Starting at $44.75

LEAK STOP GEL Copper Sulphate or Anti-Freeze
Grouped product items
Product Name Qty
Leak Stop Gel, 4 oz., by M.C. Miller


M.C. Miller Gen II Leak Stop Gel was developed for situations in which electrodes may leak CuSo4 solution in a quantity which is unacceptable. This often arises when an electrode is stored in a vehicle where the heating and cooling of night and day expands and contracts the CuSo4 liquid, forcing it through the ceramic plug. This leaves a messy residue of CuSo4 crystals behind. This situation of unwanted leaking electrodes is greatly reduced or eliminated when Gen II Leak Stop Gel is used. The gel is too thick to be forced out the end of the electrode during normal heating and cooling cycles, preventing the leakage from occurring.


 New, improved Leak Stop Gel for use with any MCM electrode. 

  • Squeeze bottle for easy dispensing 
  • Flip top for less spillage and waste 
  • Stops the leaking of CuSO4 electrodes 
  • Replaces leaky liquids with gel electrolyte 
  • Constituted from the highest purity CuSO4 crystals 
  • Retains the ability to maintain and calibrate your CuSO4 electrode 
  • Does not require heating for flow-ability 
  • Has no expiration date (unlimited shelf life) 
  • Storage temperature range : -4ºF(-20ºC) to 150ºF(65ºC)


 Preparation for Use

  • Make sure the cap on the Leak Stop Bottle is on tightly.
  • Place the bottle ofGen II Leak Stop Gel into a pan or deep dish.
  • Run hot tap water of 110°F into the pan or dish submerging the bottle of Gen II Leak Stop Gel.
  • Turn off hot tap water.
  • Let submerged bottle remain in hot water for 10 minutes.
  • Every 5 minutes run hot water again until no clumps of gel remain.
  • If no gel is observed and only liquid is present the liquefaction process is complete,
  • Remove top rod assembly from the copper-sulphate electrode.
  • Pour Leak Stop into copper-sulphate electrode to a level one inch below the top.
  • Replace and tighten rod assembly.
  • Set electrode upright in a cup (ceramic tip down).
  • Let cool for one hour or until Leak Stop has completely become a gel.

Leak Stop is a saturated CuSO4 solution. If it is desirable to verify that the solution is saturated, a few (half a teaspoon) copper-sulphate crystals may be added. This can be done immediately after Leak Stop has been added to the electrode but before hardening has started. With this done there will always be crystals visible to insure a saturated CuSo4 solution.

Removing Gel from Electrode

Replace the gel once the electrode has become used, contaminated, cloudy or varies from freshly prepared standard by 15 mV. Internal company guidelines may dictate a different millivolt variance. The Miller Gen II Leak Stop Gel behaves like a CuSo4 electrode filled with deionized water. After time and repeated use the electrode may become contaminated. When this occurs, the gel must be removed and the electrode cleaned to a bright shiny state. To remove the gel, run hot water into a bowl and submerge the electrode for 10 - 15 minutes. The Gen II Leak Stop Gel will liquefy.

The liquid Gen II Leak Stop Gel may be discarded using proper disposal methods. Rinse out the electrode tube and remove the copper element. With the rod removed, it can be sanded with brown sand paper to remove oxidation. Rinse thoroughly with deionized water and reassemble. The electrode can be refilled with Gen II Leak Stop Gel as outlined above.

Note: Leak Stop is a gel and therefore does not soak through the ceramic tip as much as a normal copper-sulphate solution. The side effect of this gain is that the ceramic tip when used in a very arid condition may dry out. This problem is easily overcome by submerging the ceramic tip of the electrode into a cup of tap water for 5 seconds. This will re-wet the tip and the electrode will work as desired.



  • TheGen II Leak Stop Gel - CuSo4 is very accurate when compared to a freshly made standard copper-sulphate electrode made from high purity crystals and deionized water. The variance can be expected to be within ±2 millivolts from a standard at the same temperature.
  • The Gen II Leak Stop Gel - Anti-Freeze is very accurate when compared to a freshly made standard copper-sulphate electrode made from high purity crystals and dejonized water. The variance can be expected to be within 1 millivolt at 32°F from the standard at room temperature (72°F).
  • At a temperature of 10°F (-12°C), CuSo4 Gen II Leak Stop Gel freezes to crystaline solid.
  • At a temperature of -40°F (-40°C), Anti Freeze Gel freezes to a crystalline solid.
  • Transition temperature from a liquid to an amorphous gel occurs at 10°F (-12°C).
  • Each 4 oz (#18010) bottle of MCM Gen II Leak Stop Gel contains enough gel to fill two RE-5 reference electrodes.
  • The 8 oz (#18020) bottle of Gen II Leak Stop Gel will fill one RE - 3A electrode.


  • Statement of Hazards: Harmful if swallowed. Causes eye irritation. Causes respiratory tract and skin irritation. May cause blood disorders, convulsions or affect the kidney. NFPA Ratings (Scale 0-4): Health=3, Fire=1, Reactivity=0. A Material Safety Data Sheet (MSDS) may be obtained by calling Farwest Corrosion Control Company or M.C. Miller Co., Inc.
  • Precautionary Statements: Do not get in eyes or on clothing. Avoid breathing vapor or mist. Wash thoroughly after handling. Handle with caution.
  • First Aid: Remove from exposure area. Flush skin/eyes with water for 15 minutes. If vomiting occurs, keep head below hips to prevent aspiration. Get medical attention immediately. See MSDS for further recommendations.
  • Exposure Limits: This substance is regulated by OSHA and or ACHIH.