Lately I’ve been getting questions along the lines of, “I would prefer to have a [blue, green, camouflage, etc.] packraft, but I read that yellow and red are easier to heat seal. Is that true?”
The short answer is, “Sort of.” Let me explain:
The notion that lighter fabric colors are easier to heat seal comes from the fact that when the fabrics are welded together, the heated area darkens slightly as the TPU begins to melt, making it look a bit wet, so you get some visual feedback to tell you you’re on the right track. That darkening is more noticeable on lighter fabrics like red and yellow, and less noticeable on darker fabrics like blue and green.
However, darkening is not the same thing as welding!
The darkening happens at a lower temperature than the welding, so if you rely on the color change to show you what areas are welded, then you will probably end up with a leaky boat.
In other words, you can rely on a lack of darkening to tell you an area has not been welded, but you cannot rely on darkening to indicate that an area has been welded (because it might just be weakly bonded and easily peeled apart).
For this reason you must rely on proper heat sealing technique to make sure your welds are secure regardless of the fabric color, and I don’t even mention the darkening in the more recent instructions.
So don’t be like the person who told me, “I really wanted a blue packraft but I ordered a yellow kit because it would be easier to build.”
If you prefer a darker color, order a darker color, and make sure you practice heat sealing before you begin assembling the kit (as I advise in the instructions). People who order yellow or red will have to practice heat sealing just as much, and if they rely on the color change to tell them when the welds are done, they will have many more leaks to seal than the person who chose the darker color and followed the steps for proper heat sealing technique.
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