Quality Control Instruments
Besides achieving the correct moisture content for the timber and concrete, the other quality requirements for the finished products. Most buyers will specify the wood coating colour according to their reference colour. In addition, the buyer will specify the gloss requirement of the coating in terms of GU (Gloss Units) based on either 20o, 60o or 85o angle of the incident light.
Colorimeters are used for checking the color of a finished and are accurate for standard colour measurements. They are ideally suited for determination of colour difference and fastness as well as routine comparisons of similar colours in production and manufacturing for quality control. They are used to specify colour. QC Inspectors carry them around to check the finish colours of their products.
A Spectrophotometer is a more complex colour measuring instrument that factors in light intensity as a function of the colour. It performs full-spectrum colour measurement, as opposed to a colorimeter’s tristimulus (a common phenomenon that occurs when two colours appear to match under one lighting condition but not when the light changes) procedure and generates colour data that’s beyond observation by the human eye. It. Colour Spectrophotometric instruments are much more expensive and are ideally suited for a broad range of applications in the research and development phase, including colour formulation and colour system development.
Gloss Meter
Gloss measurement is based on the amount of light reflected on the surface relative to a polished glass reference standard, measured in Gloss Units (GU). The amount of light that is reflected on the surface is dependent on the angle of incidence and the properties of the surface. Index units require the wood coating to have the right gloss. Trithrem's Accuscan Gloss Meters comes complete gloss calibration standard.
Gloss is categorised as either matt, semi or high gloss. In order to determine the most appropriate measurement angle start with a gloss meter set at a 60° angle of incidence.
For the furniture industry, the 60o gloss meter is more commonly used.
VISCOMETER
Viscosity is the measure of the resistance of flow due to internal friction when one layer of fluid is caused to move in relation to another layer. A common measurement unit of viscosity is the milliPascal second (mPa·s). Conversion factors are as follows:
1 centipoise (cP) = 0.01 poise (P)
1 Pa·s = 10 P
1 cP = 0.001 Pa·s = 1 mPa·s
1 Pa·s = 1000 cP
For the wood industry, viscosity of adhesives, emulsions and coatings are usually measured using Rotational Viscometer. Depending on the viscosity range, a Rotational Viscometer usually comes with many rpm speed settings with different rotor spindles. For testing the viscosity of high temperature fluids like hot melt adhesive, paraffin, or asphalt, etc, where temperature is specified, a heater can be incorporated.
Moisture Analyser
A moisture analyser determines the moisture content of a sample with the loss on drying method and consists of a weighing and heating unit (infrared). It can be used to verify or calibrate a moisture meter by putting a small sample of the previously measured wood into the moisture analyser. The analyser has a built-in weighing balance and a halogen or infrared heater to drive off moisture from products being tested. The unit is programmable to set the rate of temperature increase, the final test temperature, and other parameters. When the bone-dry weight is reached, the unit will stop the heating and the software will calculate the moisture content of the sample based on the initial weight and final bone dry weight. The test is comparable to the standard oven test except that the moisture analyser provides faster results without having to take the sample in and out from the oven at regular intervals to weigh.