DIAB Foam

Discussion in 'Materials' started by MarineSurvey, Sep 23, 2009.

  1. Ruby Tuesday
    Joined: Oct 2009
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    Ruby Tuesday Junior Member

    Herman - I am unable to discuss certain specifics at this point in time for legal reasons.

    Being an absolute newcomer to infusion, I am at a loss to explain what went wrong. DIAB handled the whole infusion process. We did a few infused panels with my vinyl ester resin during the DIAB infusion course we attended, but they never did a full-on test panel with gel coat, tie layer, CFM, etc. After a two-day course I did not have sufficient knowledge to have insisted on a test panel, unfortunately. There was a lot of bridging evident after removing the bag & peel-ply, along the chines & knuckles, where the glass had not been forced right into the mould, but those weren’t the only areas that have ‘sucked in’.

    Andrew K – DIAB hasn’t said what went wrong & have made little effort to fix the problems, or to tell me how to avoid them in future infusions.

    The laminate was as follows –

    Gel coat, tie layer 225g CSM with vinyl ester resin, cure 3 days

    450g CFM, 2 x 850 BiAx, foam, 2 x 850 BiAx, also vinyl ester infusion resin

    Peelply

    We hired the pump & catch-pots, & the resin supplier’s rep was present & did the tests with the catalyst percentages, & supervised the mixing of the resin before & during infusion. DIAB’s personnel supervised, participated & were in attendance daily from when the first layers of glass were laid in until infusion was completed. The infusion itself went smoothly, except that we used more resin than DIAB had calculated. We had longitudinal resin lines in the hull, feeding sequentially up the topsides & up the tunnel, & did the VolvoIPS implants at the same time. There were no air leaks or resin lock-outs – the hull is sound. Very little resin got through the resin-breaks & into the catchpots. Total infusion time was just less than an hour. The deck was done according to Polyworx’s programming. Infusion time around 40 mins.

    Really disappointing! I have dozens of photos & I’ll put some together over the weekend so you can see the results for yourselves.

    Cheers.
     
  2. AndrewK
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    AndrewK Senior Member

    Ruby Tuesday, based on your description it appears that the only thing done wrong was ensuring that there was no bridging during the laying of reinforcements. With infusion you have to pay attention to every little detail.
    With 225g CSM & 450g CFM, I am surprised that print through was very evident, what type of foam was used, grooved and perforated only or double cut as well?

    Cheers
     
  3. Ruby Tuesday
    Joined: Oct 2009
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    Ruby Tuesday Junior Member

    Hi Andrew, the feedback I'm getting from third parties is that the 225 CSM is far too light in this application, & that CFM is primarily a resin-transfer medium, not a print blocker. Some say that a 2mm Soric layer would have helped a lot. Print through was very, very evident over 100% of the hull & deck!

    I've infused a panel with gelcoat, 450 CSM, cure, 2mm Soric, 850 BiAx, 6mm core, 850 BiAx. It was absolutely perfect when it came out the mould, but within two days it had started to show the BiAx printing through. After a few days in the sun it's as bad as the hull & deck were (without the bridging)

    We used both types of foam, with the curves of the deck using more of the double cut than the hull.

    I thought by using DIAB's services that they would have 'paid attention to every little detail' & made sure there was no bridging! It's a pretty daunting undertaking infusing a 42' cat, especially when you've never done it before.

    Thanks for your interest, I'll keep posting if anything new comes to light.

    SeeYa
     
  4. rwatson
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    rwatson Senior Member

    What colour is the gelcoat?

    Dark colours are renowned for print through in the sunlight for epoxy, so I guess VinylEster would be worse. One boat builder leaves his boat under cover for a month before exposing it to UV.
     
  5. Ruby Tuesday
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    Ruby Tuesday Junior Member

    G’day RWatson - The gel coat colour is white, or WAS white – it’s now an International Paints undercoat, after four weeks of filling & fairing.

    The hull & deck were both in their moulds for at least two months after infusing, while we made up & fitted bulkheads & floors etc. The painter I have repairing the hull & deck refused to do any work on them until I had post-cured them, as he’d had similar problems (also with a DIAB infused boat incidently) in Western Australia. We put tents over the hull & deck & used gas heaters to heat them up to 65 degrees C for a few hours, & we still noticed a bit of movement. As I understand it, infusion resins have a very low exotherm (curing) heat while under vacuum & once out the mould & exposed to sunlight, they can continue to cure & distort.

    I saw a Princess at Riviera recently ($4m second hand!) & its hull was dark blue & it was unbelievably bad! The entire hull had serious print-through problems. Doesn’t help much knowing that I’m the only one having problems. I still believe in spite of all my hassles that resin infusion is the way that boat-building will be going in the future, but it will be a long & expensive learning curve for most. Making the infused components for the bulkheads, floors & even fuel tanks on a flat table was very interesting & rewarding work, & once you have the hang of it, it is really very simple if you follow the rules, or as AndrewK says, “you have to pay attention to every little detail”. Very true.

    Cheers
     
  6. rwatson
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    rwatson Senior Member

    Interesting you mention Riveria. One Diab dealer has a lot of pre-cut kits of foam and cloth that they are trying to unload since Riveria went broke.

    I am about to try a hand laid Vinylester over Diab foam layup on a 28 footer.

    I have some trial material to hand - it will be interesting to see how it turns out. I will be using Diab Divilette as the foam coating rather than CSM. This print through problem is a worry.
     
  7. waikikin
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    waikikin Senior Member

    Hi rw, using a core bedding putty is a reliable way to go, there's less chance of print with plain sheet with vent holes or with knife cut rather than saw cut contour foam so far as "block print" goes. All the best from Jeff.
     
  8. Herman
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    Herman Senior Member

    Also take a critical look at your resin.

    I sell a lot of polyester resins in NL, and I have plenty to choose from. (for various applications). Some do shrink much more than others. I have abandoned already a couple of resins due to excessive shrinkage.

    So ask around, get a couple of samples of resin, and do tests. I do the same in NL, as a supplier, but not every supplier is willing to do that.
     
  9. AndrewK
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    AndrewK Senior Member

    Ruby Tuesday, infusing any size boat for the first time is daunting, you did the right thing by hiring DIAB's expertise to guide you through the process but unfortunately they let you down.
    Print through is a separate issue, CFM is just as effective as CSM for blocking print through. I have only infused with epoxy but a friend had infused with Huntsman AME600 vinyl ester and 750g triax on both sides of 16mm grooved foam and I had not noticed any print through.
    You mention only the biaxial showing up but not the blocks from the double cut foam.
    I would expect the other way around especially in curvy areas where the slits open up.
    What is the resin supplier saying?
    Is there any evidence of resin gassing up and collecting between the biaxial yarns or are the laminates translucent and void free?

    Cheers
    Andrew
     
  10. Ruby Tuesday
    Joined: Oct 2009
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    Ruby Tuesday Junior Member

    Thank you all for the positive & helpful advice you are offering, it is all very much appreciated.

    Attached are (I hope) some pics of the hull & deck so you can see the issues I have. The gel coat was sanded back with 80#, and then sprayed with a high-build primer. This was then also cut back & the remaining voids were filled. The pics show the hull with the (white) filler, while the deck is ready for filling. You can see that even after all this sanding there are substantial areas that need filling.

    The resin manufacturers have said that their resin is in no way responsible – end of story. It’s impossible for me to prove otherwise, but I’m not convinced it didn’t contribute - there was further shrinkage when I post-cured the mouldings two months later, in spite of their chemist telling me there could be no more shrinkage after the first week. Several people have refuted his statement, even from within his own company. There’s not a lot of choice in Australia in infusion vinylesters. One’s made by the same company & marketed under different names.

    I am starting to have doubts about the wisdom of using 850g BiAx – it’s a very coarse fabric as you can see from the print through. I’ve had a number of people look at the boat & some have raised this issue, saying a tri axial would have been preferable, & would have conformed to the chines & knuckles far easier.

    Andrew - The foam was used with the resin grooves & cuts facing inwards so there was no evidence of any print through from it. Where there were tight curves, we “V’ed” the grooves until it fitted, but never had the grooves facing the mould. I infused all the bulkheads, etc, & had no problems at all, although that’s far easier to control than a 42 foot mould, & there was no gel coat or tie layer involved. I wasn’t aware that you could use CSM during infusion? During the course we did it was demonstrated that CSM is very poor for resin flow. We used it in the resin breaks (peel ply & CSM) to slow down resin entering the vacuum lines. The laminates all appear to be void free.

    I’m stumped - & out of pocket!

    SeeYa
    View attachment DeckInfusion 001.zip

    View attachment DeckRepair 002.zip

    View attachment Hull Infusion 004.zip

    View attachment HullRepair 003.zip
     
  11. Landlubber
    Joined: Jun 2007
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    Landlubber Senior Member

    Ruby,

    The CSM is used prior to the infusion game, it is laid over tissue that is laid oved the gelcoat, and set down by hand. It is cured before the setup for the infusion, that way the "outer" skin is hard and shown less print thru.

    I have had very good results using their barrier coat, on a dark blue hull you need everything you can get.
     
  12. Herman
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    Herman Senior Member

    I know above is not the route you wanted to go. Anyhow, the end result will be great, however, with more expenses then expected. So be it for this time.
    If you ever want to go this route again, please be aware that there is also available some easily sandable gelcoats. (we call them "sanding gelcoat", but I guess we are not creative...)

    The resin is not responsible? What did shrink then? All polyester and vinylester based resins shrink further somewhat at curing. I must also say that postcuring is an art in itself. Please do not ramp up the temperature more then 10 degrees C / hour. This implicates you need to be able to control and distribute the temperature. Ramp up untill you have reached your target temperature. Keep it there the desired amount of time, then ramp down again, or just turn of heating, and keep the oven closed.
    About choice of resin: I guess we are lucky in Europe. Stil I do suggest ordering samples of polyester and vinylester from as many places as possible, and test them. If there is no expert available, you just need to be the expert...
    We have a mould which produces a half-round piece of rod. The mould is exactly 400,0 mm long, and made of polyester. The most slippery of mold releases is applied in it. Resin is cast in it, and allowed to cure. After demoulding, the sample is measured. After postcuring, it is measured again. This will give you insight in the behaviour of the resins. At least you can compare them.

    Do you have a picture of the biax? Is it a 0/90? These can be pretty course. Best is to plan a +/- 45 on the outside, as these are usually a lot nicer.
    CSM can be used in infusion. However it needs to be no more then one or perhaps 2 layers, and needs backed up by more permeable material. For instance, infusion of a panel made from 450 CSM / Soric / 450 CSM is no problem.
    However, in this case, layup should be (and probably is):
    Gelcoat
    Optionally a barrier coat
    Optionally a veil
    Low tex CSM
    Peelply

    After cure you can remove the peelply (carefully) and then build up. You could start with a Soric TF1,5 or 2, to prevent further print. All is optional, and you can perform some tests to see what works for you.
     
  13. AndrewK
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    AndrewK Senior Member

    Ruby Tuesday, the more open (lover fiber volume) biaxial cloths are good for infusion due to the larger channels between yarns. I use a 600gm2 version for infusion but do not have issues due to much lower shrinkage epoxy resin. Same goes with triaxial some have large gaps between yarns, out of the 4 cloths available locally I found that the cheapest actually wet out most easily, draped best and had smallest gaps between the yarns.
    I also use CSM at times for resin breaks this is emulsion bound stuff. But also have found that DB with CSM backing actually infuses faster than DB without the CSM. The reason for this is that the CSM is stitched to the DB and not emulsion bound.

    You say that the infused bulkheads had no print through, was the 850g biax used in these?
    If it was then I would recommend that the below mentioned panel you made, you sand through the gelcoat/CSM/soric and check that the biax did infuse correctly.
     
  14. Ruby Tuesday
    Joined: Oct 2009
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    Ruby Tuesday Junior Member

    Landlubber – who is the “their” as in “their barrier coat”? I think I may have missed something you posted? The process DIAB used is essentially as you have described it.

    Herman – Thanks for the technical information, I’ll be trying those out shortly. The BiAx is 0* & 90*, & at 850g is very, very coarse. Others have suggested that a lighter (600g or 650g) DB would have been far more suitable. Also a heavier tie layer than 225 CSM would have helped, as would the Soric. All this expert knowledge I expected would have been provided by DIAB.

    Andrew – The main bulkheads were two layers of 850g BiAx on each side of the 25mm foam, & the thinner floor supports were 2 x 650 BiAx each side of 12mm foam. The surface on the under side is smooth as, & the top side is typical peel ply finish.

    Trying to digest all this information, plus supervise the repairs to the boat, & keep the internal build going with the hull & deck, leaves little time for experimentation. I’ll have to mould the hard top, sliding roof & radar arch soon too, but I’m seriously considering laying these up by hand until I know a lot more about infusion. If the experts can’t get it right, I don’t know if I’m likely to.

    Thanks to all for the input. Cheers.
     

  15. Landlubber
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    Landlubber Senior Member

    This is a copy of the layup of a boat we did in Shanghai with Diab.
    The resins used are DSM, as follows:
    The end result showed very clear on the gelcoat surface, as you can see the RAL 5003 is a dark blue, difficult colour to get right.

    DSM Gelcoat RAL5003
    DSM Barrier Coat
    300 CSM
    VectorPly E-LTM2408 ( 813g +275g mat )
    VectorPly E-BXM1708 (600g(+-45) +275g mat )
    VectorPly E-QX3600
    VectorPly E-LTM1808 (600g(0/90)+275g mat )
    Diab H100 pvc core 20mm
    Diab H80 pvc core 20mm
    450CSM
    VectorPly E-QX3600
    VectorPly E-LTM1808 (600g(0/90)+275g mat )
     
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