Water Jackets


We have been asked many times if our tanks are water jacketed, they definitely are. We have also been asked why.

We have also been asked why we do not make “Direct Heat” tanks.

Why are your tanks water or (liquid) jacketed? By liquid, this can also be oil or a glycol solution.


Here are some of the reasons:

What does “Direct Heat”, referring to a tank mean?

  • If it doesn’t have a Liquid Jacket….It is a Direct Heat Tank. There is no other way around it. Direct heat is where there is no liquid jacket surrounding the inner tank of a double jacketed melting tank.
  • Basically Direct Heat tanks have two jackets or tanks. One inside the other. Some are square, some are round.
  • Direct Heat tanks have heating coils, band heaters, etc. surrounding the inner tank. These coils or bands are attached to the inner jacket in some manner. They generally have some insulation surrounding the coils.
  • This direct contact of the heating coils can create “Hot Spots” that can burn your oil or product.

85% of our customers are involved in making some type of body care product.

  • Body care products should not be made in a “Direct Heat”, (No liquid jacket). You are asking for trouble.
  • At some point in the heating and making of the product you will get hot spots along the perimeter of the tank.
  • Any liquid, such as a vegetable oil, lotion, herbal tincture, etc. that may come in contact with direct heat surface can get overheated, scalded, burned. Once this happens there in no going back and your product has now become inferior.
  • There are certain tried and true methods that cannot be cheapened or disposed of in handling, natural, organic, or vegetable based materials.
  • This is why your how-too books and formulas online require you to use a Double Boiler for balms, liquid soaps, lotions, etc. A double boiler is a good start for beginners to make small batches and it helps eliminate the possibility of “Overheating”
  • Direct Heat tanks have a much higher incidence of fire hazard. Coils and band heaters can burnout. This can result in electrical sparks.
  • Direct Heat, is more energy efficient…< not true >. It may heat a little faster (about 27% faster) but requires more energy to stay warm and looses heat much faster (78% faster).

Where would you use one of these direct heat melters?

  • Candle wax is okay to use with one. Caution must be used if a band or coil burns out and sparks.
  • They cool down quickly so they work well for short runs. Not so well for day after day use because you have to heat the air space around the tank and actually some heat is lost on the outer shell. A liquid jacket tank with an insulation jacket can stay warm for many, many hours, definitely overnight.
  • Petroleum products would do well in one.
  • Heating water, mixing fertilizers, chemicals unaffected by hot spots, etc. would be fine in a direct heat tank.
  • You can, with constant stirring, get by using these tanks for delicate materials. Just make sure you do not stop until the process is complete.

Make no mistake about it….if it does not have a “Liquid Jacket, then it is a “Direct Heat” Tank (melter).

And, if you are going to be making any M&P, CP, HP soap, lotion, balm or body care product where you care about the quality of….Do Not use a Direct Heat melter.