Real World Test Results
Scientific Furniture Tests and their Relevance to Laboratory Applications
By Durcon Technical Services
These tests are reflective of the worksurface’s resistance to the major chemical substance classifications (acids, bases, and solvents). Because it is impossible to be 100% sure of the top’s performance against any unlisted substance, we recommend the customer check using a sample and the actual material in question. It should be noted that some materials stain the top rather than chemically harming it. This group includes silver nitrate and zinc chloride.
Rockwell Hardness “M” Scale
The results obtained from this test are useful measures of relative resistance to indentation of various grades of plastics. However, the Rockwell hardness test does not serve well as a predictor of other properties such as strength or resistance to scratches, abrasion, or wear, and should not be used alone for product design specifications.
Water Absorption ASTM D-570
This test measures the amount of water absorbed during immersion in water. It is most relevant to applications where high humidity or long term submersion in water may be present as service conditions for the product. The state of the material after it is removed from the water (any separation of layers or swelling) should also be taken into consideration when evaluating the test results.
Fire Resistance ASTM D-635
This test measures the material’s response to being subjected to an open flame. The sample is marked with start and finish lines. The flame is applied for a set period of time and then removed. The sample is judged on the time it takes for the flame to travel between the lines, or whether it ever gets to the starting line after the flame is removed (if not it is self-extinguishing).
Heat Deflection ASTM D-648
This test reflects the temperature at which the material bends under pressure and heat. It is most relevant to high heat applications or very long term medium heat conditions like an oven or high temperature bath that is constantly operating.
Flex Strength and Flex Modulus ASTM D-790
The flex modulus refers to the rate at which a material deflects (bends or sags) as weight is put on it.
The flex strength refers only to the breaking point. If the material bends significantly before it breaks (as epoxy tops do), the bending (modulus) data is more relevant than the breaking data, because earlier bending would be detected as distortion of the top before the top ever broke. This is particularly true in shelf or cantilever type applications.
For these reasons, in most design work, the flex modulus should be considered more important than the flex strength.
Specific Gravity ASTM D-792
This can be compared to get an idea of the relative weights of various products. The specific gravity is the ratio of the weight of the material as compared to the weight of the same volume of water. The density is the material’s actual weight per unit of volume.
Compressive Strength ASTM D-695
The compressive strength test refers to the strength of the material as it is squeezed across its thickness (compressed). The compressive strength of epoxy material is generally far greater than that of the casework below it. It is so much greater that it is practically impossible to apply enough weight to the casework/top assembly to get the countertop to fail in a compression mode before the load is too heavy for the casework to bear.
Tensile Strength ASTM D-638
Tensile strength is the strength of the material as it is pulled from end to end like stretching a rubber band. As with the compressive strength, this test reflects the material behavior under conditions not reproducible under normal conditions.