New Boat with Print Through .

Discussion in 'Boatbuilding' started by CFCC, Jun 23, 2014.

  1. CFCC
    Joined: Jun 2014
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    CFCC Junior Member

    Hi - I'm very new here - first post . I'm a member on theHull Truth but couldn't come up with anything in searches over there . I have an issue and don't know if its a disaster or slightly cosmetic. Noticed on my sea trial the other day that the new 25' CC (white) i'm purchasing -I could see Print Through of glass matt on port / bow area. It was slight but in the right light you could see it. I couldn't feel it …..Right away I bring it to attention of builder. He says its the material . Ya no kidding …..But I want it gone because I'm a freak with sharp lines and properly taken care of hull . He says lots of boats have it and you can wet sand it away. What I've read here - it has something to do with laminating resin shrinking and cure ? It can possibly come back? I don't have pics - it was so bright - phone wouldn't pick it up. my first impression -is it was not enough gel coat …..How does wet sanding fix this - Is there anything else I should be concerned about ? Thanks for any help.
     
  2. waikikin
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    waikikin Senior Member

    CFCC,
    shhh, not so loud, everyone will want some;)
    Jeff.
     
  3. slneatboat
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    slneatboat Junior Member

    I would not say lots of boats have it, far from it I would say. It is a defect not structural maybe, but even so it is a brand new boat I wouldn't like it.
    Some possible cause's to ponder:
    Gelcoat applied to thin
    Starting to lay up when the Gelcoat was to green (not hard enough)
    Perhaps a bad area in the mould in which case it could be rubbed out no problem. If it is print through in the boat it could perhaps be rubbed out depending how serious it is,
    if not more Gelcoat needs to added and then rubbed down. I wouldn't have thought it will come back again as everything should have cured by now.
    Steve.
     
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    There are a few reasons for print through, none are desirable and all can be easily avoided in production.

    Depending on how deep the print through is, sometimes it can be buffed out, but you must remember, you're removing gel coat in an area where it's too thin already. I've seen folks "burn through" trying to fix this. The best way is more gel coat, faired, then smooth to blend in to surrounding areas.
     
  5. UNCIVILIZED
    Joined: Jun 2014
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    UNCIVILIZED DIY Junkyard MadScientist

    Hi,
    Preface: There's a lot of information in here on fiberglass boatbuilding which may be WAY basic for you (or, just the opposite). I included it as; I don't know what your knowledge level is, and, much of it's relevant to your query regardless of what your depth of experience with composites is.
    Also, some of what I state may sound a bit dire, & or doom & gloom. But, knock on wood, most boats are overbuilt to begin with. Though with that said, your problem's still definitely worth looking into.

    So... yes, OP, you're correct in that what you're seeing is/may be something to be concerned about. And while I'm not an expert, from what I know, given your description, it may be far more than cosmetic.

    The gelcoat being a bit thin is one possible reason, as already noted. And I'd highly recommend against trying to wet sand or cut polish out the marks which you're seeing. Because if the gelcoat's already so thin that you've got print through, I, personally, would be REAL leary of making it thinner yet.

    Next, I'm assuming that the boat was built with fiberglass resin... given that you mention both; gelcoat, & mat. Things which aren't much used in production boats built with epoxy to the best of my knowledge.

    The thing is, when a boat's being built, one of the things which is supposed to happen is that the fiberglass resin is supposed to dissolve the binders in the mat, turning it into a smooth'ish surface in between the gelcoat and the first structural layers of glass in the hull. The idea being that the mat then prevents print through of the weave pattern in the; woven roving, stitched, or woven glass on top of it.
    This is it's purpose; by physical design, & chemical makeup.

    You may have a problem, & you may not. If you do, a few which come to mind off of the top of my head are:
    - improperly catalyzed resin. Which could cause problems both with the strength of the resin itself, as well as with the laminate's layup.
    Part of the latter being that with goofed up mixture ratios, if there are layers of mat laid into the laminate in between layers of woven roving (or other structural cloth layers), which is the norm. Then poor resin quality control has prevented the mat from achieving it's proper physical properties & state, thus it's possible that it's not going to properly bond the other layers in the laminate stack together.
    Plus, the resin will never fully cure, nor subsequently, completely achieve it's full strength.
    - Note: Getting the correct catalyst to resin ratio is a bit trickier than at first glance, as with a Lot of the resins out there, this ratio is/can be temperature & humidity dependent.

    In boats build with fiberglass resin, it's common for them to be built with consecutive layers of fiberglass mat, & woven roving, stacked on atop another. And in this type of construction, a good bit of the mat's job is to help to bond the heavy layers of woven roving together.
    Part of what is supposed to happen in this type of construction is that the styrene binders in the mat are supposed to be dissolved by the fiberglass resin. Thus, the mat's fibers are then free to "flow", and to fill in the "gaps" in the thick, heavy weave of the woven roving.

    The styrene in mat is what holds all of those short to mid length fibers which comprise it, together. IE; the way it looks at room temps, in a pre-glassed state.
    And since woven roving is so thick, & has a lot of high & low spots due to it's weave, it needs a bit of help (something of a filler if you will) to assist it in bonding to the next structural layer in the laminate. In addition to the resin that is.

    Resin of course helps with this (filling in the gaps/highs & lows) to some degree. But due to roving's thickness caused by it's weave, it needs some assistance, in order to achieve a more monolitihic, strong, structural layup. One without any air gaps, or thick pockets/areas of resin between layers.

    I'm hoping that my explanation is making sense. I suppose another way of alternatively stating this, about the specifics of what I'm saying is this:
    If you take a piece of heavy weight roving, say 24oz (per square yard) & lay it on a table top it's easy to see all of the peaks & valleys in it. And thus, it's fairly easy to visualize that if you laid another piece of roving on top of it, there would definitely be a pattern of gaps between the two pieces.
    While things like vacume bagging after wetting out the roving would definitely help to minimize such gaps, mat is more or less meant, by design, to fill in said gaps. And it's tougher for the mat to do so, if it's binders aren't dissolved by the resin.

    Like I said, I'm not an expert. Thus, in addition to doing more digging around online, I'd suggest contacting a few companies (live AND electronically) which deal with/in these materials, with your questions & search for knowledge.
    And I'm guessing here, but odds are that some of the various folks (both who make resin, as well as those who make/sell fiberglass) will have FAQ's sections on their websites.
    If naught else, by doing said type of digging, you'll add to your knowledge of how boats are put together.

    Ah, also, I know for a fact, that both System Three Resins, & West System Epoxy have tech help lines. And have always been happy to talk to me and field my questions. Likely they'd be willing to field some of yours too, even regarding non-epoxy queries. And or they could point you in the right direction towards more info sources that'll help.
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    If it is a new boat in pre-delivery, why not bring it up with the dealer before completing the sale, it has to be regarded as a fault, and not one that the buyer ought to have to fix.
     
  7. Steve W
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    Steve W Senior Member

    Lot of doom and gloom, I don't know what kind of boat you have but sometimes print through is just a function of a builder placing weight savings ahead of cosmetics. It is indeed not at all uncommon, at least in performance sailboats to have print through of not only the structural glass (not mat) but also the balsa core blocks. In most cases it could be wet sanded and buffed out if so desired. In most cases a boat with no print through will be heavier than it needs to be, builders who place cosmetics ahead of all else will often include extra layers of various materials in an attempt to block print through which while achieving that end, add considerable extra weight for no structural gain. While thin gelcoat is not great neither is thick gelcoat.

    Steve.
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    Print-through is more obvious with certain coloured gelcoat, and it really gets down to how evident it is, if it sticks out like the proverbial, I would have had a word to the dealer.
     
  9. CFCC
    Joined: Jun 2014
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    CFCC Junior Member

    thanks for replies . So a bit more info for you folks. I did not see chopped strand mat print thru - I saw what looked like fine mesh plaster tape pattern-(squares ) They were smooth and not wavy from what I remember . My Fiberglass/boat building skills = probably a 2 on a scale to 10 being the best ….Even though I just did a bunch of small repairs on my current boat to cosmetic stuff. But I did learn about spraying gelcoat and catalysts etc. Catalysts are tough to measure -gelcoats are tough to spray etc …. I'm still not sure of types of glass used in the process -even though I have an idea how its all done. I think the mold is waxed/prepped - then gelcoat is sprayed in - then a loose glass (is it strand?) is layer in by hand and resined . Followed by more layers creating a ply - now I know theres different types but I don't know which are used . This boat is not a top tier manufacturer - It is a small custom builder - who has a great rep . It Is A Light Go Fast CC Hull …..I only had a small window to come down and water test the boat - I'm from out of state . But we had a motor issue (300 Yami) wouldn't start - something to do with fuel pump - Which is a blessing in disguise because a storm like I've never seen rolled in and we would have been on the water when it hit -possibly with a dead motor ……I had to fly out next day with family issues at home - MIL is very sick . But before the test I noticed the print thru …..I got a lot of $$ into this boat and the electronics are rigged ….What can I do - what do I have done in terms of an inspection ? Can a surveyor tell if the Resins were F'd up and its all going to fall to pieces down the road by testing etc ?
     
  10. PAR
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    PAR Yacht Designer/Builder

    Sounds like a finish cloth, not mat, if it's a uniform cross hatch pattern. This would mean the gel coat is too thin in this area and/or they should have used an outer layer of mat or a combo fabric with the mat up.

    Print through isn't as uncommon as you'd exspect as noted, though on a new build, I'd like to see it corrected, while you still have a chance to argue with them about it.
     
  11. ondarvr
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    ondarvr Senior Member

    Shrink and print, the problem that haunts every fiberglass manufacturer, is it something structural to worry about...rarely, but there is a possibility.

    All resins shrink, and some of the stronger more costly resins may shrink a bit more, resulting in more print than resins that are formulated for cosmetics as the primary goal.

    Trying to pin down the exact reason for print on this hull from a distance over the internet with no pics or history of production would be difficult at best, but here are some common reasons.

    Cool temperatures during that portion of the build, even an open door at that end of the shop can create a slight localized under cure in the skin resin. The residual cure takes place at a later time from it being exposed to higher temperatures and it shrinks at a different rate than the surrounding area. This can happen while it's still in the mold, or afterword's, but it typically shows up as an area with more surface distortion than on other areas on the hull.

    Pre-release can cause a bit more localized print too. A portion of the hull can come loose from the mold during the build, this allows that area to shrink on the gel coat surface a little more than what's still in contact with the mold.

    Overlaps or thick areas in the laminate may show up due to the higher temperatures reached during the cure cycle, which may result in more shrink.


    Thin or under cured gel coat may show a little more print.

    Under catalyzed resin may cause print. I shouldn't really say under catalyzed, it may just have a lower amount than required for a timely cure at the ambient temperature at the time.

    There are many other reasons for print through, but more details of how it was built and what products were used would need to be supplied.



    Edit: I had to stop mid reply and do some other things and in that time you supplied a bit more info.

    Like others said, it appears the cloth (although rarely used in a build like this) is printing through, other than being visible it probably has no detrimental effects structurally. This happens frequently and is normally taken care of in the detail department prior to it going out the door. If you don't like it have them sand and buff it, this is what's normally done before the owner sees it.
     
  12. CFCC
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    CFCC Junior Member

    how is it corrected at this point ? Is the last layer the one against the gelcoat or is that the first ?
     
  13. CFCC
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    CFCC Junior Member

    Ill have more answers tomorrow on build process /products . Thanks
     
  14. ondarvr
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    ondarvr Senior Member

    Sand and buff.

    The first layer is against the gel coat.
     

  15. SukiSolo
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    SukiSolo Senior Member

    I assume by the term 'Print through' you are referring to a pattern visible on the gelcoat surface? Normally this reflects the cloth type in the outer layer under the gelcoat. So you may see several different patterns depending on the boat, the builder and materials chosen. If this is the case and it is a very, very light pattern, it can indeed be cut down with 1500 grit and buffed out.

    Whilst this is a little unusual on a brand new build, it is found on just about every FRP build I have ever seen after some years. The better ones might take 10 years but eventually they will show this 'print out'. Basically it is caused by very, very slight resin shrinkage and rarely is a structural fault or even a build fault. More of a QA problem than true fault. If you visit a yard you should be able to pick out, woven cloth patterns, woven roving patterns, Chopped Strand Mat patterns etc. It is a little like varnish on wood, which sinks into the pores over time so whilst perfect new, after 5 years a light grain pattern can be seen on the surface.

    Generally it is rare to find this defect on a new boat but if the hull is more than say 6 months old it may have had sufficient time for it to show up. Just for fun, I would say it will show up again in a few years time, but after another very fine cut, will probably never show again as full shrinkage and settling will have occurred.

    On race dinghies, I would expect the surface to show a light ammount in the first 6 months of life. The hot boys are aware of this and flat out with superfine and buff out to a perfect surface. Worth remembering that the usual initial gelcoat thickness should be around 0.5 to 0.8mm. If it is more than 1.0mm it tends to crack too easily. At normal thickness, removing the high spots of the pattern is removing hundreths of a mm only, so no need to worry about losing integrity.
     
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