Technical Testing data

Testing methodology

To replicate the weathering effect of our two biggest enemies, sunlight and humidity, we employ advanced ‘accelerated weathering’ techniques. UV lamps and a humidity chamber expose samples to extreme environmental conditions and these damaging elements are applied many times faster than they would normally occur in nature.

One of the best machines available for testing by this ‘accelerated weathering’ process is the Q-LAB QUV/SE. It exposes up to 24 samples to UV light (340nm band) which closely replicates the UV power of the sun’s radiation. Because humidity is also a big contributor to degradation in gelcoat, plastics and other coatings, we also create the effect of night dew by allowing humid moisture to condense on the test panels.

For the technically minded, we test in accordance to Astm G 154-06 (cycle 6) – the “standard practice for operating fluorescent light apparatus for the exposure of non-metallic materials”. This is a repeating cycle of 8 hours of UV light (Uva-340 @ 1.55W/M2/Nm, and 60°C) followed by 4 hours dark condensation @ 50°C.

Very few accelerated weathering machines can actually do all this, but at Tribos, we only trust the results of objective scientific analysis, so we insist on the best equipment like the Q-LAB to test Tribosdurability and performance to the limits and beyond.

DURABILITY TESTING

During product development, we test for durability under ‘normal’ usage. The ‘wash durability’ test replicates the normal washing process – with soap and a sponge – such as any owner or employee would undertake.

For this test, we use a standard panel (an aluminium plate coated with black polyurethane paint finished to a specified level of gloss) treated with our Tribos polymer barrier.

We then place the panel into a special laboratory ‘washing machine’ that replicates two strokes with a sponge, at 10n vertical force, while immersed within a 0.5% solution of solids (sodium dodecyl sulphate) in water. Following this wash, the test panel is rinsed and dried, the gloss measured and the whole cycle repeated up to 300 times.

All Tribos products last at least 250 of these simulated washes, which can be compared to 500 firm strokes with a sponge in soapy water.

COLOUR CHANGE MEASUREMENT

Judging the ‘yellowing’ and colour change of a surface finish by eye alone is both difficult and subjective, so just like every other aspect of our testing, we rely on accurate scientific measurement to determine the performance Tribos delivers.

Our X-Rite Colormuki spectrophotometer measures spot colours in both RGB and Lab standards. We mainly use Lab colour because it is the most accurate for quantifying ‘yellowness’. Lab colour is expressed as a 3-digit number:

  • L: Measure of lightness, where L is white and 0 is black.
  • a: Green/Red, where -100 is full green and 100 is full red
  • b: Blue/Yellow, where -100 is full blue and 100 is full yellow.

Since we are really most interested to establish the rate of colour change – and there is a colour movement not just within the b component but within the a component as well – we use the following calculation to express the colour change as a single number.

LAB Colour Measurement Visualisation

LAB Colour Measurement Visualisation

 

Δ Colour/t = √ (Δ a² + Δ b²)
             ---------------
                    t

Where:

  • Δ a = change in a component from the initial value of a.
  • Δ b = change in b component from the initial value of b.
  • t = the cumulative number of hours exposed.
Tribos is a registered trademark of Tribos Coatings (International) Ltd