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Enhancing the permaflate

This section describes corner taping. Read it for information, and note permaflates are now all supplied with the tube corners already taped.

'Enhancement' does not refer to the buying of yet more bits from the maker, to personalise your already costly airbed. What will be covered here is modifications that involve mostly time rather than cash. Enhancing performance by corner-taping will be covered in detail. If campers find any more ways to enhance permaflate performance, this is where they will appear.

The basic permaflate tube, located in the centre of the airbed where the most pressure occurs, has a life of about a year if slept on each and every night. Since most of us do not camp full-time, this translates to an estimated life of ten years or so. The permaflate began only three years ago, so real-life figures, for how long a permaflate tube lasts the average camper, will not be available for some years yet. Tube failures after a year of life on my 'testbed' have been remarkably consistent. Wrinkles, on or near the two corners at the foot of the tube develop at high stress points. The polythene kinks and deforms at one point, and eventually at this point a hole very slowly develops. The point at which the hole opens varies from tube to tube, but it is invariably between the welded corner and about two inches up the side of the tube. The 'testbed' of course leaves the tubes in the same place they are inserted for the whole year of life.

It may be argued that because under intermittent use, where the tubes are reloaded into the sheath almost every time the airbed is used, tubes will rarely end up in the same place in the sheath twice running. High stress breakdown is thus unlikely, since the point of stress keeps shifting. The tubes will thus last for ever.

Alternatively, since the inflated tube is slid into the sheath a great number of times, it may be argued that we will see wear developing on the foot corners of the tubes from simple abrasion against the sheath. The tubes will thus not last as long as expected.

Corner-taping is the process of sticking a length of fibre-reinforced adhesive tape over the corners of the tubes. The tape runs about three inches up the side of the tube, completely covering the area where stress holes develop. The fibres in the tape are not very elastic, so stress deformation of polythene film stuck to them is prevented, and of course the entire area subject to abrasion now has an armoured coat over it. We do not corner-tape the tubes, because as a small maker the process is time-consuming and fiddly, and would price the tubes out of the reach of most. With a projected life of ten years for the tubes in normal camping, other disasters are more likely to claim a tube. Regardless of this, if you want to enhance your permaflate by corner-taping the tubes, we would compliment you on a good move.

We already use 19 millimetre or 0.75 inch wide fibre-reinforced tape on the sides of the permaflate sheath. The tape comes in big rolls, from a specialist industrial tape supplier, who describes it as cloth-backed adhesive tape. Taping all corners of seven tubes uses less than ten feet or three meters of tape, but small rolls of this specialist tape do not seem to exist.

We are prepared to hand-spool ten feet of the tape we use onto any centre core that we have available, and supply this with a permaflate order, for an extra $2. Once you have tried the permaflate out a few times, you will be able to judge if expending the time required to corner-tape is worthwhile. Plainly if the airbed impresses, and will be used heavily for a long time, you tape. If it doesn't, you don't.

Taping procedure

This shows one lower corner of a permaflate tube. The side up to 3 inches up the ruler is to be taped.

About 3.25 inches of tape is cut off (the adhesive is white). Just under half of the width of tape is stuck to the end of the tube as shown. Alignment is fiddly, can be repeated if you peel off the tape, and does not have to be precise, although good alignment looks pretty on the tube ends. Note the tape extends beyond the welded corner, so it covers the corner. If it extends too far it can be {carefully) trimmed afterwards so the extension is only two or three millimetres.

If you have got the alignment right, when you fold the tape over and stick it down, the result looks like this. If not, leave it crooked since it will function just as well, or carefully peel it off and have another go. The tape will survive three or four attempts, but cut a new piece after that. If you find the technique relatively easy, go ahead if you like, and tape all four corners on each tube. If the process is slow and difficult, taping the foot corners (the opposite end to the stopper) will give you most of the benefits.