JEC COMPOSITES MAGAZINE - Issue #67 - August/September 2011 - 44

coating

Fig.3: QUVA delta E 1000-hour accelerated weathering test results Fig.4: Florida 12-month natural exposure delta E test results Fig.5: Florida 12-month natural exposure delta b* test results, which measure the degree of yellowing

1000-hour QUV exposure delta E test results
Accelerated QUV testing was carried out in advance of the longer term Florida testing. Good performance under accelerated UV weathering conditions is an indicator of good long-term natural weather performance. The graph (Figure 3) shows the delta E colour change results of the four gelcoat technologies tested after 1000 hours of accelerated UV exposure. The delta E value is 3.20 for Crystic Permabright compared with 4.03 for the best-in-class Iso/NPG.

base resin (Figures 4 and 5). All four sets of gelcoat plaques were tested at the same time and subjected to 12 months of continuous exposure in Florida. Both delta E and delta b* (db*) colour change measurements were taken. The Florida colour change test results showed the colour stability performance of the gelcoat to be even better than the accelerated QUV indications. The 12-month Florida natural weathering test results for Crystic Permabright measured a delta E of 1.25 and a delta b of only 1.06. By comparison, the best-in-class marineapproved Iso/NPG had a delta E of 2.25 and a delta b* of 2.20. These colour change results are highly significant as the smallest colour difference that humans can detect with the naked eye is a delta E of 1.0. So, the exceptionally small colour change in the Crystic Permabright test plaque is virtually impossible for most people to detect. Additionally, the delta b* test results confirmed that the new advanced polymer gelcoat base with its deconjugated Iso/NPG polyester backbone, when used with the right pigment and UV additives, could significantly reduce yellowing in a white or cream gelcoat. This was a key project deliverable for the luxury yacht market, who is keen to use a gelcoat which would help maintain the showroom look and condition of a vessel for longer. The Florida test results clearly show that the new gelcoat is able to do this, providing two times better colour stability than the next best-in-class Iso/NPG and four times better than a standard isophthalic gelcoat. This dramatic improvement in gelcoat colour stability is a step change in technology for the industry.

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Outstanding Florida 12-month UV exposure results
Scott Bader has independently tested Crystic gelcoats in Florida for a great many years. They have concluded that Florida weathering is the most accurate way of predicting how a gelcoat will resist harsh UV light over a prolonged period of time and so it is a key test for a Crystic gelcoat product to pass. This is because the extreme natural exposure conditions in Florida accelerate product weathering by an order of two to three times faster than most other locations. Once again, comparative tests were carried out between the standard Iso, the best-in-class Iso and the best-in-class Iso/NPG versus Crystic Permabright gelcoat with its new formulation and D-Iso/NPG

jec composites magazine / No67 August - September 2011

Osmotic blister performance
Alongside weather resistance, excellent
JEC COMPOSITES MAGAZINE - Issue #67 - August/September 2011

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #67 - August/September 2011
