unwaxed fiberglass resin no air dry?

Discussion in 'Materials' started by wrbowcal, Aug 12, 2012.

  1. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    I fully understand the reasons for using a product other than roving, there is no disagreement on that. Yes it could be slightly lighter for the same strength using a different fabric, but this makes little difference.

    What people are forgetting is that this is a repair being done on an old school hull that was built with roving and held up for 30 plus years. The owner rebuilt it with the same products that survived those first 30 plus years with no failures. The original build was designed with roving in mind, it can be rebuilt with either product and easily survive another 30.

    Again, this is a non issue on this repair.
     
  2. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    To say 50% of the glass is doing nothing is ********. Imagine what would happen if 100% of the strands were all arranged the same way either with or across the stringers.

    I don't know tunnels, I'm beginning to wonder about your obsession with fiberglass. Your hair on fire method of "teaching", (whether anyone asked for it or not) is getting tiresome.
     
  3. rxcomposite
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    rxcomposite Senior Member

    Agree it is a non issue but over engineering? Hmmm.

    If it can be made better and be a better boatbuilder, why not?

    Here is why from Composite Design Guide by Terry Richardson.
     

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  4. tunnels

    tunnels Previous Member

    Great minds think alike !!!
    Hows things ??
    :p
     
  5. wrbowcal
    Joined: Apr 2010
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    Location: Crowsnest pass, Alberta

    wrbowcal Junior Member

    I had some left over from another project.I take it its not that strong correct?
     
  6. tunnels

    tunnels Previous Member

    Please dont get me wrong !! i like to make people think about what they are doing !!, things they have done purely from habit and never given any thought because thats what we do ,we dont think !!

    Like i said 50% of the fibres are doing absolutly nothing !!

    Believe me when i say you are not along ,i have pissed off many seasoned surposed expert laminators and even had the odd harsh word or two from a know it all composite engineer that didnt understand the basics of how the job was going to be done !! .
    I have even had the odd forman leave the premesis and stayed away for 3 days because i told him he wasnt doing his the job properly !!! as the job progressed we did become good friends later as the project got further on ,he even suggested a few things as well because he stepped back and looked at what had been done and how he could improve what he was doing !!.

    At the beging of any project regardless of size I always look at whats being used and how its being used and think how can we make it better yet not have to work harder .
    Like has already been said cut the cloth at a 45 degree angle and all of a sudden you have 100% of the fibres working for you and they are not just there for a free ride everywhere all the time !!.
    Am i making any sense ??:confused:
     
  7. rxcomposite
    Joined: Jan 2005
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    rxcomposite Senior Member

    To answer wrbowcal question, it is a good idea to finish flowcoat the inside because;

    1. You are using wood as the core
    2. Your last layer is a WR.

    Coating it with a flowcoat (resin + wax) is an insurance that your bilge will be sealed of all pinholes and prevent water ingress.

    If you need to attach or do a secondary bond to the inside, apply peel ply on the bond area and scour it with 40 grit sandpaper after peeling off the ply before a secondary bond.

    If this is a bigger boat, I would advice having the last layer of light CSM.

    It is the resin rich layer that stop water ingress be it a pipe, the outside of the boat, or the bilge area.
     
  8. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    Flow coating helps if the laminte is thin, if there are multiple layers of glass and they are wet out properly it won't help much, if at all. It will help if the laminate is exposed to UV light because the fibers will bloom (become exposed and turn white), in this case UV9 can be added for a little more protection.
     
  9. rxcomposite
    Joined: Jan 2005
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    rxcomposite Senior Member

    Fibers don't bloom and it is white in color in the first place. You must be talking about resin degradation due to UV light.
     
  10. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    Its referred to as fiber bloom because as the resin breaks down from UV light it exposes the fibers and they appear white again. The fibers are near the surface, so it doesn't take much degradation of the resin to expose them, when encased in resin they're clear. In the corrosion industry (industrial chemical tanks and piping) it's not uncommon to leave the resin uncoated (no paint or gel coat), they just use the same resin for flow coat and add UV 9 to reduce the bloom on stuff that will be used outside.
     
  11. wrbowcal
    Joined: Apr 2010
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    Location: Crowsnest pass, Alberta

    wrbowcal Junior Member

    I really should have put wax in the mix on my final layer but didn't have any and forgot to fill the hull with styro sm too before bedding the floor down with long strand filler and screws...hot Sunday lots a beers..I will have to get foam pumped in now.

    The original stringers were cleaned,sanded covered in woven roven wetted out with a .5 hr resin set then quickly screwed the new stringers on while wet let set and cover all with another layer.The old rib was a hardwood rib and broke so I epoxied three 5\8 hardwood plywood together and countersunk 1.5 " down into the stringers,Rib and stringers were both cut should be minimal lateral movement.I had to cut grooves down the underside of the floor to bend down the 5/8 floor with a jack to the corners ya its taking longer than I thought.Maybe it will pull the sides up to the original shape floor was .5 " high on the sides.
     
  12. wrbowcal
    Joined: Apr 2010
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    wrbowcal Junior Member

    TUNNELS I do agree the woven should be a tighter weave like the mid weight cloth I have its a real heavy tight weave,didnt have enough handy for two layers but would have used it instead and easier to work with. The roven seems to expand to much when wet making application over corners difficult too because it lifts.I hate it! expensive too.I will have to dig up the receipt and find out what the other cloth was.

    OH I never thought of cutting the cloth at 45 deg angle never did it on other projects also.Thanks will do from now on.
     
  13. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    Are you saying you used only roving and no mat under it or between layers?
     
  14. wrbowcal
    Joined: Apr 2010
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    wrbowcal Junior Member

    Yes I didnt use mat under or over it just two layers of roven.Sounds like it would have been a good idea.Used it on my cruiser floor worked out good underside of floor and over and gelcoated.I hope with the light weight of the speed boat I wont have any issues.Is it good practice to use mat with roven?
     

  15. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    Now the bad news.

    Roving, or any other fabric, needs mat for a good bond, without it it's almost a worthless laminate.

    Without mat there will be a resin rich layer between the roving and substrate.
    Polyester is weak and brittle on it's own, it relies on the glass for strength, so this resin rich layer will fail when the hull is stressed.

    Frequently you can grab a corner of the roving with pliers and pull it off easily.

    Not finishing it with waxed resin is survivable, so is using roving instead of biax, not using mat can be fatal.
     
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