ASMT D3363 is a test method designed to evaluate the hardness of a coating through the use of pencil or drawing leads. The cure of the coating may also be assessed by this standard. Lastly, this test protocol may be employed after an accelerated aging test in order to characterize the evolution of the hardness of the material over time. For instance, ASTM D7869, which is based on the ASTM G155 practice, is an example of a method that could be paired with ASTM D3363. Micom offers ASTM D3363 testing as part of its paint testing services
ASTM D3363 Uses and Factors to Consider
Evaluation of the film hardness by a pencil hardness test
The purpose of this test protocol is to determine the hardness of a coated film through the use of pencil hardness measurements. This method consists of evaluating the surface aesthetics of the coating following an attempt to scratch it with a pencil of known hardness at a 45o angle by applying a constant force. In fact, if the sample is sufficiently large and flat, it is possible to an apparatus such as the one shown in Figure 1 to accomplish this step. However, when the specimen is small and in 3D, it is necessary to perform this action manually. This process is repeated with a pencil that is lower on the hardness scale until the two endpoints are reached. The first is the hardest pencil that will leave the film uncut and the second is the hardness pencil that will not scratch the specimen. Lastly, this standard is employed as a tool to determine the level of curing of the coating and it may also be used for development and production control purposes.
The main factors that are to be considered when running this test are the film thickness and the type of pencil.
ASTM D3363 Typical Experimental Parameters
The size of the sample has to be specified, but it needs to be sufficient to realize the experiment twice. Table 1 lists the typical test parameters.
Table I: Typical test conditions for ASTM D4587
|Temperature||23 ± 2 °C (73.5 ± 3.5 °F)|
|Relative humidity||50 ± 5%|
|Film thickness||To be specified|
|The range of the wood pencil hardness scale||6B||5B||4B||3B||2B||B||HB||F||H||2H||3H||4H||5H||6H|
Other Test Methods Related to ASTM D3363
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