Gluing Tivek with 3M 927

  • 20 Oct 2020 17:03
    Reply # 9315099 on 9002951
    Anonymous member (Administrator)
    Bonjour

    A new trial today with a more sophisticated seam. It is glued with 3M 927 -25 mm wide tape then sown with a zigzag in the middle of the glued area.

    The seam resisted to 60 kg (daN) before tearing slowly.

    The seam started to tear appart from the end of the zigzag stitches where, with the return end there are more punctures. The failure was very slow and homogeneous: the zigzag was torn and the glue film was pulled appart on both area above and under the zigzag.

    It seems that the zigzag prevents the glue film to peel off. Once glued it should be quite easy to sew a zigzag in the middle of the seam.

    Eric
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    Last modified: 20 Oct 2020 17:32 | Anonymous member (Administrator)
  • 18 Oct 2020 22:31
    Reply # 9311453 on 9002951

    There is just one thing though - when I glued Tyvek with basting tape I found the glue join was much stronger than the tyvek cloth itself, in this particular respect: Tyvek is very strong if you try to rip it or tear it - even the lightweight tyvek I had was very strong in that way.

    But it is not a woven cloth - it seems to have random fibres which are held together in some way I don't understand, but the point is, it is not difficult to pull the top fibres away from the body of the cloth. The result of that was, I found the glue joint to be very weak with regard to unpeeling the join. The glue-to-tyvek did not fail, but the top fibres of the tyvek came away very easily with the glue.  (I think your photograph of the failed join shows this quite well - you can see the result on the surface of the remaining cloth.)

    I don't know what happens in sheer, but if you pull the joint apart perpendicular to the cloth, it failed quite easily for me.

    Maybe that is not a problem for a sail, I suppose the joins are always in sheer. I don't know enough about the mechanics of a sail, maybe the glue join  is fine - but I would not expect it to be as strong as the glued join on a woven cloth such as dacron, which I think would stay intact until the glue itself failed.

    Tyvek seems incredibly light for its strength, it makes me think it could be ideal for a dinghy sail and warrants further investigation. In the US I believe there is a UV resistant version, but I was unable to get that in New Zealand. Its not particularly cheap here in NZ, but for a small sail that does not matter. Tyvek and tape would seem to me to be a pretty good way at least for a "quick-and-dirty" experimental sail, and better than the usual "polytarp". It is also very soft and I am guessing it would be perfect for barrel-cut or other simple methods of quick making cambered junk sail.

    Added - sorry for repeating so much, I did not check what was already written before.

    Last modified: 18 Oct 2020 23:05 | Anonymous member
  • 18 Oct 2020 17:58
    Reply # 9311166 on 9002951
    Anonymous member (Administrator)

    Bonjour
    Today, I’ve conducted an other traction test with the same configuration but with the two pieces of Tivek sown together (One row in zigzag) for 10 cm.
    The jonction failed at an effort of about 30 kg. The Tyvek torn following the needle punctures.
     
    So gluing Tyvek seems to be much more effective, 50kg against 30 kg  and it is easier and faster by the way, than sewing it  !

    Eric

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    Last modified: 19 Oct 2020 09:23 | Anonymous member (Administrator)
  • 01 Jun 2020 17:20
    Reply # 9007066 on 9002951

    Thank you Greame

    For my experiment, I added a plastazote bloc under the system to absorb the choc following the failure test! It was not suffisant. The tub was already half cracked and it opened completely. I had 40 liters on the shed floor to mop !

    Idealy I would have liked to mold the Tyvek but the equipment is too expensive. It would have provided an homogeneous structure.

    I tried Sikaflex 291i but while peeling the mastic was separating too easily.

    Tyvek is also very sensitive to puncture and is very easily cut ! (I will have to avoid any sharp item !)

    I’m happy not to be the only one to test Tyvek; I felt a bit lonely !

    Next step will be to pull on a 10 cm thread to know if it is really stronger than the glue. The sowing machine needle perforates the Tyvek and build a structural weakness : tear along the doted line !

    I’m thinking about a bow mast (I’ve sailed a Finn years ago, a very pleasant and powerful boat) but I’m a little afraid of resonance effect that could amplify the movement of the hull in specific conditions (headwind in confused sea for example).

    https://www.ocqueteau.com/notre-gamme/tilapia-650-cat-boat.html,9,6,0,0,103#.XtUhXsbgo0o        (2.50 mn)

    As a start, I already have a mast on Mingming and will keep it. 

    The demonstrator’s flexible components are here only to push the concept to the limit and show if it’s viable or not.

    As the demonstrator didn’t break while it was built so lightly without reaching the expected failure test, even in high wind, it validated the concept.

    The prototype, Mingling's flexible wingsail will be much more robust with 8mm rod GRP structures and a Tyvek skin.
    Eric

  • 30 May 2020 23:52
    Reply # 9003813 on 9002951

    Hi Eric, when I saw your experiment, I could not resist showing a similar apparatus I used a few months ago to test panels of plywood sheathed with ferrocement.


    Water added 1.0 kg at a time, deflection measured and recorded for each increment.  A good method (except testing to failure results in a real mess to mop up afterwards!)


    I made one of the panels on my SJR from Tyvek.

    The parts were held together with basting tape and I considered leaving it that way, but did in the end run a line of stitching over all of the seams. I have since replaced it and would not use Tyvek again for a larger sail, though tape-glued it should be very good (and very quick) for a dinghy, as the material is very light for its strength. It is not woven in any direction, so next to impossible to rip. It will stretch a little. Lovely and soft to handle. I found, when ripping a seam held with just basting tape, that the glue line was strong enough. The glue would not yield from the surface, but the surface would tear from the body of the cloth, which is what defines the strength limit of the glued joint. Rather like gluing cardboard surface to surface – the glue itself is not the weakness. Tyvek is OK to sew – but be careful if you put a hot knife near it!

    edit: I just checked and found the the Tyvek I used was 43 gsm. That was all I could get in New Zealand and I see it is much lighter than the material you are using. 105 gsm sounds like a really practical proposition, though the strength of surface-to-body adhesion is probably no better. I would definitely run a line of light zigzag stiching over the seams, and imagine the result might be very good indeed.  (Once the parts are stuck together, the sewing is the easiest, quickest and most fun part of the whole job). The material, with its randomly dispersed fibres, is nice and soft and seems to have some properties which might be quite good for a cambered junk sail. I see also that in the US you can get Tyvek with some sort of UV resistant component in it, which would be even better. 

    I do rather like the idea of re-purposing domestic components or light industrial materials in boat building , where possible, as an alternative to specialised branded marine products.

    Your flexible rig is a real hoot (approving laughter) – to take your philosophy to its proper conclusion, why not a bendy mast as well? (eg like the old Olympic Finn class). I am guessing the flexible components would not readily scale up to larger sizes – but who knows what the rig of the future will be. Inflatable perhaps!

    (Here is an inflatable wingsail, which I think has been on the forum before. http://inflatedwingsails.com/en/concept/    Variable camber, too!)


    Last modified: 18 Oct 2020 22:48 | Anonymous member
  • 30 May 2020 14:17
    Message # 9002951

    Bonjour
    I’m experimenting Tyvek (105g/m2) as a prototyping skin for Mingming’s wing.
    I tried to glue Tyvek with 3M 927 in 25mm wide. It is the glue tape that is used by sailmakers to assemble spinnakers made out of membranes and not cloth.
    I made a 10cm test piece.

    I hanged in the shed and hanged underneath a baby tub. I then poured water into the tub 10 liters by 10 liters with a watering can.

    Once at 50 kg of effort, after about 1mn, the test piece split and the tub fell on the ground.
    The glue film parted but the glue didn’t unstick from the tyvek on either side.

    I’ll use it for the remaining panels of Mingming’s wing. It is much easier and faster than sewing long threads.

    Unfortunately, the baby tub, a very old one, split open while falling ground, so I couldn't conduct a similary trial with a 10cm seam. I must first find an other baby tub !

    At least, it seams a good way to assemble prototype.

    Eric

       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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