Quality control tests in manufacturing environments are key to ensuring the finished product meets the agreed specification and is consistent across different batches.

For liquid products a viscosity measurement is used, but when your finished product is a solid or semi solid (like a paste, cream, compact powder or very thick or sticky liquid) this isn’t possible.

Penetration tests are used to assess the consistency of these sort of products – and having been used in the oil industry for years, the range of applications is now branching out into food, cosmetics and other industries.

We’ve taken a look at penetration testing, and how it can be applied in a range of manufacturing industries below.

What is a penetration test?

When a product will not flow, a penetration test presents a good alternative to assess consistency.

The test begins with a penetrometer unit which holds a penetrometer cone. The cone can vary in weight, shape and material to suit the type of sample you are testing.

The sample of product is packed into a sample cup, and then placed underneath the penetrometer cone. The cone is aligned to be just touching the sample surface, but not yet pressing into it.

When the test is lined up, the cone is released and falls into the sample – this is where the sample consistency matters, the softer the sample, the further the cone will fall.

After a set time period, the operator reads the penetration depth off the penetrometer in mm, and this is recorded as the result.

The depth can be read off the penetrometer down to 10th’s of a mm, so provides a very accurate assessment of the sample consistency. With manual penetrometers, the reading shows on a dial (as seen above), but digital penetrometers that display the reading on a screen are also available for increased accuracy (shown below)

The time, temperature, amount of sample and cone are all variables which are controlled in each test – either to suit the product or to comply with specific test method protocols such as ASTM or IP methods.

What products can be tested on a penetrometer?

The tests are widely used in the petroleum industry to assess lubricating greases and waxes, but an increasingly wide range of other products can also be tested by this method.

Some of the products currently supported by Koehler Instruments penetrometers and accessories include;

• Grease
• Petrolatum
• Bitumen
• Asphalt
• Chocolate
• Confectionery products
• Yeast
• Fats (e.g. butter, margarine, lard)
• Jam or Marmalade
• Ketchup
• Mustard
• Fruit
• Lipstick
• Compact powder
• Cosmetic creams
• Paints
• Solid emulsions
• Pastes
• Honey-like fluids

Many of these tests can be conducted to industry specific standards, though other products could also be tested using self-developed methods.

For more information about penetrometers and penetrometer cones to go with them, follow the links above or contact us with any questions;