Here is a crazy line I got fed today and I want to know if any of you knew if this was true or not. So I went to a local surf shop today to pick up a white fin box as the white fin box on a used board I just bought is cracked through. The dude behind the counter tells me that they only have black ones but black ones are stronger anyway cause they don’t have to use pigment to make them. I bought one anyway because I needed a fin box not because I believed his line. It got me thinking though. Could this be true? After all, the fin box that cracked through was a white one.
The base materials for injection moulding grades of plastics are all different. Some are crystal clear like Polycarbonate, some are milky like Polyethylene, others are a natural colour like Nylon 66 (an odd faun colour).
Adding lots of pigment to a plastic (white or black) would affect the mechanical strength (i.e. reduce it) of the plastic to some degree.
However if you add a reinforcing material like milled fiberglass, a dramatic improvement to the mechanicals is seen. Too much fiberglass percentage in the plastic can make the plastic more brittle but will have a high break strength.
So my guess is the black ones must have milled fibers, the white one must not (or possibly too much but unlikely), assuming they are both made of the same plastic.
They’re both made of the same plastic, glass filled polycarbonate. Not sure on the percentage, but i think its around 20 to 40 per cent. Should be the same amount of glass in each color. Titanium oxide (white pigment) weakens the plastic substantially more than the black pigment. Just get 1 of each and drop them from about 2 feet up onto concrete and listen to the difference. Black one sounds tinny while the white one has a deeper thud sound.
…I used Brazilian boxes that are really better than FU boxes…in quality, in design and in materials…the only good thing about FU is that they have the smallest boxes…
…the blacks and the whites Brazilian s boxes are equal strong…
This is why Swaylocks rules. At first I thought the perverbial “dude” behind the counter was nuts, but he got me thinking and now we have the answer to a question none of us ever really thought to ask. Once you go black…
Thanks to all for the insight and to the sarcasm crew…may your decks be ever delaminated and your fin boxes be white
Much Stoke
Mr. T
“I pitty the fool who uses a white fin box with a 10 inch fin!”
Logboy was heading in the right direction with his description. But, fell short in his conclusion. The real reason that black boxes are stronger than white boxes is that it takes a larger concentration of pigment to make the base material white than it does to make it black. The strongest boxes would not have any pigment in them. But, there is far more to be gained in changing base materials. Just look at FCS’s change from cheap ass PVC to polycarbonate.
Being that I build both windsurfers and surfboards, I have only seen the stronger used boxes made out of plastic that is black. If you really want a strong box use a Chinook box. It is a windsufer box that is installed on several high end longboards. I hit a fish going 20+ mph on my windsurfer and the only thing that happen was the fin tab was bent. The hit did catapult me off the board. There are several box manufactures in market. Some are better than others. I have found that some of the ones coming out of Asia are not up to the higher quality of the Western boxes.
Aloha! The white boxes always seem to de-lam along the edge after installation, whereas the black ones almost always seem to stick. Also, I’m pretty sure that the Chinook box is milled out of a solid piece of material, while the regular ones are two parts. Aloha…RH