That special bond!

28 February 2019

Degafloor bond testThe longevity of resin flooring depends on a number of factors. Whilst high quality products and installation expertise are the two most obvious requirements for success, another factor that can make or break the outcome is substrate testing.

Substrate testing is vital in ensuring product longevity and compatibility and it can be carried out in a number of ways. Degafloor advise conducting a bond test and feel this is the most effective technique to achieve reliable results. This is especially true given the increasing number of quick curing, fibre reinforced, large aggregate free and dense screeds available. Whilst many are compatible with Degafloor systems, there are some that cure with a hard, closed surface and high density, which prevent Degafloor primers from penetrating sufficiently to achieve a reliable bond.

Additionally, concrete additives and surface curing agents can also have an impact on the primer. Therefore, it is essential that bond tests are carried out on all screeds and substrates prior to installation. Conducting a bond test will confirm whether a reliable bond can be achieved and whether the substrate has sufficient tensile strength. Various bond tests, with various primers can be carried out to ensure the most suitable primer is chosen. One primer does not fit all!

Other tests to include is a rebound / Schmidt hammer test to assess compressive strength. For MMA based systems, the compressive strength must be at least 22.5 N/mm2. We also advise taking a moisture test to determine whether a moisture tolerant primer is required.

To achieve a successful bond test, the following instructions should be followed:

Mix the following thoroughly:

  • 500 grams resin (whichever primer is being tested)
  • BPO adequate to installation temperature
  • 1500 grams 0.1–0.3 of natural quartz

Once all ingredients are mixed together:

  • Apply a 150 mm wide pancake, 5 -15 mm thick and wait to fully cure, ensuring the pancake is cold.
  • Using a hammer and bolster hit off at a 45° angle. This should be difficult to remove. If the pancake just slides off, it is a fail!
  • The aggregates should be sheared off / split upon removal, which indicates a good bond. If the aggregates have not split and have just been pulled out of the substrate, this means the substrate is weak.
  • A Schmidt hammer will be required to test for compressive strength.
  • The pancake should have at least 60% of the substrate adhered to the back.
  • Bond test results should be kept as evidence that this process had been undertaken. A photo should be taken of the bond test and the substrate side by side.

To simplify the substrate testing process, Bond Test Kits (0.1 – 0.3 mm) can now be purchased from




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