Knowledge Base

Knowledge Base

The Faster, Safer Way to Clean Rotational Molds

Feb 13, 2020, 20:03 PM

Stoner Molding Solutions A320 Mold Cleaner Concentrate

Any molder who cares about quality parts understands how important it is to remove grease, grime, mold release, resins, and colorants that contribute to discoloration and poor mold performance. Properly maintained molds increase overall efficiency and productivity, creating better parts with less scrap.

But, while most molders agree that mold cleaning is necessary to turn out quality parts and protect molds from damage, many don’t agree on the best cleaning method to employ.

It’s not hard to understand why they disagree when you consider the vast range of resins, molds, and processes used in modern manufacturing. While no single mold cleaning method will be ideal in every situation, this article covers the three most popular methods for rotational mold cleaning, along with our pick for the fastest, safest method to clean rotational molds in most molding operations.

Ice Blasting

Ice blasting is a non-abrasive cleaning method first popularized by rubber molders for its ability to clean hot molds in the press without creating additional waste.

Ice blasting uses solid carbon dioxide pellets (the size of a grain of rice) or shavings (the size of a grain of sugar) shot at high velocity to remove residue from mold plates and tooling.

The key advantage of ice blasting is that the process is not abrasive and won’t damage tool steel or hardened aluminum. The technique also works well for textured or polished cavity surfaces. Ice blasting is also very clean since it doesn’t produce dust or waste.

While many operations choose to take their molds offsite for ice blasting by a third party, small, portable ice blasting equipment is also available that can be used in-house.

Despite the advantages of this non-abrasive cleaning method, ice blasting comes with some serious drawbacks as well.

Ice blasting is noisy, producing a shrill whistle at levels over 102 decibels, and so good ear protection is required. But even when earplugs are used, the noise can be irritating when utilized for extended periods.

Ice blasting can also be a safety hazard. Ice pellets moving at an average speed of 900 feet per second can seriously wound human flesh. The force can also cause mold plates or tooling to blow over or launch into the air, creating additional safety concerns.

While effective at removing most build-up, ice blasting is not very effective at removing heavy stains or rust, especially when used on the large molds used in rotational molding operations.


Solvent cleaners, like Stoner’s 93234 Cut Mold Cleaner, are very effective at removing grease, grime, mold release, resins, and colorants from molds. In fact, solvents are a popular cleaning method used for injection molding.

However, due to the large size of most rotational molds, molders will need a lot of solvent for effective cleaning. This can be expensive since the price of solvents often rises and falls with the cost of petroleum. In addition, solvents aren’t particularly effective on cross-linked, water-based mold releases.

Solvents also release fumes that can adversely affect indoor air quality or contain allergens that can impact workers. Removal of these fumes requires proper ventilation. Many solvents are also flammable, creating a risk of fire.

Water-based Cleaners

Water-based cleaners like Stoner’s A320 use a powerful, high pH solution to cut through colorant build-up, grease, oil, dirt, stains, and mold release within minutes.

Unlike solvents, water-based cleaners do not produce fumes and are non-flammable, promoting a safer working environment.

Water-based cleaners are also very economical since molders add their own water to the concentrate. A typical gallon of water-based concentrate will yield 5 to 7 gallons of cleaning solution for just $20.

Cleaning Rotational Molds with Stoner’s A320 Water-based Cleaner

  1. Make sure the tool is at room temperature.
  2. Spray the tool with A320 diluted with 5-7 parts water.
  3. Keep the tool wet for about 10 minutes. Respray as necessary.
  4. Scrub the mold with a green scrub pad. Wet the pad first to promote easier cleaning. A brown scrub pad can also be used for more aggressive scrubbing when needed.
  5. After scrubbing, wipe down the tool with a water-soaked cotton towel.
  6. Repeat spraying and scrubbing as necessary.
  7. Wipe down the whole tool with a wet towel to complete cleaning.
  8. Preheat the tool to evaporate the water before re-applying water-based mold release.

As you can see, the water-based mold cleaning process is simple and doesn’t require loud tools or high pressure like ice blasting. This makes water-based cleaners our pick for the fastest, safest method to clean most rotational molds!

Have Questions About Mold Cleaning & Maintenance?

The experts at Stoner Molding are always happy to help! We’ve been helping manufacturers mold more parts in less time since 1942. We formulate and manufacture a wide variety of mold releases, mold cleaners, lubricants, and rust prevention products designed to optimize your production process and improve your bottom line. Contact us today for a FREE sample!

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