How should I microwave the Lava Rocks?

The time needed to activate the Lava Rocks is dependent on the strength of the microwave being used. Be sure to microwave the Lava Rocks for half the time listed, turn them over, and resume microwaving the Lava Rocks for the remaining time.

1800 watts: 1 minute each
1500 watts: 1.5 minutes each
1000 watts: 2.0 minutes each

Place the Lava Rocks side by side flat in the center of the turntable.  Do not boil, heat on stove, or heat in oven.  To prevent eruption or other damage, heat on LOW in 30 second intervals, tipping the Lava Rock back and forth, and turning them over each interval.  OBSERVE THE PACKS WHILE HEATING.  If any expansion of the pack is observed at any point during heating the microwave MUST BE TURNED OFF IMMEDIATELY.   Allow the expansion to recede before handling.  Do Not heat for more time than is stated.   Do not place warm pack directly on a surface that may burn.  Use oven mitts to remove the packs from the microwave and hold them by the semicircular gripping tabs.  Heating is compete when the interior material is fully melted and can be felt to run when the Lava Rock is gently tipped back and forth.

What If I don't know the wattage of my microwave?

Refer to your microwave manual to determine wattage. If you do not have the manual, contact the microwave manufacturer.

As a general guideline you can also determine the strength of your microwave by observing how long it takes to boil one cup of water. 

Place 1 cup of water in a microwave safe cup. Include a non-metallic spoon or stirrer in the cup. Place the cup in the center of your microwave and begin microwaving it for 3 minutes. Observe the water through the glass while microwaving. Stop the microwave when the water begins to boil. It does not need to reach a rolling boil.

Find the amount of time it takes to boil one cup of water in your microwave oven in the first column, "Water Boils". The number next to it under "Microwave Strength" is a close approximation of what wattage oven you have.

Water boils (minutes) ................Microwave Strength
....1:45 .........................................1,000 watts
....1:27 .........................................1,200 watts
....1:10 .........................................1,500 watts
less than 1:00 ..............................1,800 watts

For those of you wishing for a more specific test, you may perform the following:

1. Pour exactly 1000 milliliters (mL) of cool tap water into a microwave-safe container. Using the thermometer, stir the water for about 10 seconds, then measure and record the temperature. For accurate results the initial water temperature should be between 60 degrees F (15.6 degrees C) and 80 degrees F (26.7 C).
  1. Place the container on the center of the oven cooking shelf. DO NOT leave the thermometer in the container. The cooking shelf (tray) or turntable must be in place and any metal racks must be removed.
  2. Heat the water for 33 seconds at full power. Use an accurate digital timer or stop watch if the oven has a mechanical timer.
  3. After the heating time is completed, immediately remove the container, stir the water for about 10 seconds, re-measure and record the temperature of the heated water.
  4. Subtract the starting water temperature (step 1) from the ending water temperature (step 4) to obtain the temperature rise.
  5. To determine the output power in watts, multiply the total temperature rise by a factor of 100.
  6. Example:
  7. Starting temperature (T1) = 60 deg F
  8. Ending temperature (T2) = 72 deg F
  9. Subtract T1 from T2: 72 - 60 = 12 (temperature rise)
  10. Multiply temperature rise by 100: 12 x 100 = 1200 watts
  11. The test may be repeated to insure accuracy


Why isn't my Lava Lunch staying as hot as I thought it would?

  1. All microwaves perform differently, and all microwaves degrade over time. Therefore, there will be some differences in performance from microwave to microwave.
  2. Performance will vary based on several factors. These include the type and strength of your microwave, the amount of food packed, the containers used to hold the food, the type of food, and the temperature of the food when packed. We have all had the experience of having our french fries cool faster than the burger, or the broccoli cooling faster than the chicken - this is due to differing masses, water content, and differing surface areas. Unfortunately, these variations cannot be controlled.
  3. Be sure that the food is reaching 160 degrees Fahrenheit or greater when packed. As a guide: off-the-stove-top hot is about 180 degrees, and just-out-of-the-oven can reach 200 degrees on the surface. A comfortable temperature at which hot food can be consumed is around 140 degrees. For best results, pack your meal as hot as possible.
  4. Be sure to use Lava Lunch with the zipper closed and keep it closed. Opening and closing Lava Lunch frequently will allow heat to escape. Be sure it's zipped tightly. Any opening in the lid will also allow heat to escape and so it will not stay hot as long.


What can I do if my Lava Lunch isn't staying hot for as long as I would like?

  1.  If you are not achieving the desired results, you may increase the heating time of the Lava Rocks by 30 seconds combined heating time when heating both Lava Rocks together.  On day one, try increasing the combined heating time of both Lava Rocks by 30 seconds to see if that resolves the issue.  If you are still not satisfied, you may try an additional 30 seconds of combined heating time for both Lava Rocks on day two.  We do not recommend exceeding 5 minutes combined heating time (for both Lava Rocks together).
  2. For best results place the Lava Rocks side by side on the turntable during heating, and flip them over when half of the heating time has expired, then continue heating for the remaining time.
  3. For best results pack one Lava Rock beneath your food, and one above.


What is the best way to clean and care for my Lava Lunch?

Hand wash with mild soap and warm water. Allow to air dry completely. Do not use bleach. Do not machine wash.  Store in a clean, dry place.   


How should I pack my food in my Lava Lunch?

While any food container can be used with Lava Lunch we have found that food stays hotter, longer, when food is packed in stainless steel containers.

Additionally, we have had best results when placing one Lava Rock beneath your food container, and one on top. Although you may try different configurations.  If you are experiencing heat transference to the upper compartment, try placing the Lava Rocks on the sides of the food container, or placing both of them beneath the container.


Place the Lava Rocks side by side, on the turn table, in a clean, dry microwave.

Heat the Lava Rocks for the recommended time on the label of the Lava Rocks that associates with your microwave strength.

Heat the Lava Rocks for half of the recommended time, turn them over, and continue heating them for the remaining time.

To remove the Lava Rocks from the microwave, grasp them by the gripping tabs located on the sides of the Lava Rocks only.

The center of the Lava Rocks will be HOT.


The Lava Rocks are designed to be heated in a clean microwave. Leftover food particles or grease may cause hot spots which may damage the Lava Rocks and void the general warranty concerning the lifespan of the Lava Rocks.

Do not heat the Lava Rocks beyond the recommended times. Overheating the Lava Rocks can cause damage to the Lava Rock and may result in damage or injury.

DO NOT expose the Lava Rocks to open flames as the packaging will melt and may catch fire.

Allow the Lava Rocks to completely cool to room temperature prior to heating in a microwave oven or re-heating in a microwave oven.

DO NOT leave the Lava Rocks unattended while heating.

DISCONTINUE USE if the Lava Rocks leak fluid during the heating process or if you notice any expandion, or disfigurement of the Lava Rock container.



Does Lava Lunch come with a warranty?

Yes, it's covered by a limited warranty against manufacturing defects. This warranty does not cover damage resulting from improper use, normal wear and tear, accidents or improper handling. If you feel you have a defective product, you must email info@LavaLunch.com to begin the warranty claim process.


What is your return policy?

If you are unhappy with your Lava Lunch purchase for any reason, you may return it within 30 days of purchase provided it is undamaged and in re-salable condition, and we will refund the price of the product.  Items must be returned in brand new, unused condition, with all hang tags and packaging intact. Please ship returned items to the address on the return authorization form.

You will be refunded for the merchandise total, plus applicable sales tax paid, less a re-stocking fee of $3.50.   Shipping and handling charges are not refundable unless the product arrived damaged or the incorrect product was shipped. Please allow 14 business days for us to process your return. Please allow 1 to 2 billing cycles for the credit to show up on your credit card statement.

Please include a note in the box with your name, address and reason for return or exchange. Your refund or exchange will be processed as soon as the item is received. Please email info@LavaLunch.com to begin the return process.


No Exchange Policy
We do not accept orders or items for exchange. If you need a different size, color or product please return your item(s) for a refund and place a new order at your convenience. Placing the new order now just ensures that you will receive it quickly, and that it won’t go out of stock.

Returning Damaged Merchandise Purchased Online
If your merchandise was damaged in transit or is found to be defective upon arrival, please email info@LavaLunch.com to arrange for a replacement. We will ask you to provide photos of the damage for our internal research purposes.