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Thread: Making fibreglass skins

  1. #1

    Making fibreglass skins

    Im 3/4 way through my tinny rebuild, and up to the walls. It previously had 3mm ply walls and they were sealed and carpeted. This time around, Id like to make fibreglass skins, then paint and splatter paint them prior to fitting.

    How do i make the skins ?

    What do i lay the glass on, that will easily pop off once cured ?

    I was Told a melamine board and wax it with carnubua Wax that you use for cars. is this correct ? any other sure proof ways to do this ?

    Thankyou

  2. #2

    Re: Making fibreglass skins

    Melamine will work, not sure on the wax, but to be sure either buy some "proper" wax, or try a small piece and see how it releases.

  3. #3

    Re: Making fibreglass skins

    Form ply could also be used. Perhaps google your local fibreglass supplies and ask them what release agents they sell.

  4. #4

    Re: Making fibreglass skins

    I have previously used melamine board. Not all carnuba waxes are the same. Some automotive carnuba waxes contain cutting compounds and silicone. Gelcoat will not sit over silicone. Mould release wax is carnuba but designed for the job. Apply 5 coats ,rubbing off between coats. allow an hour between coats for the wax to cure and release any solvents. An electric fan works well to cure wax.. For a positive release,apply Release agent (liquid) it will dry similar to plastic skin. Not all mould waxes are PVA release agent compatable.
    Hope this helps.
    tug tellum
    Not all tools are usefull.
    Nappies and politicians should be changed regularly for the same reason..

  5. #5

    Re: Making fibreglass skins

    Yep melamine will work. As will a sheet of black builders plastic. (No wax needed on plastic.) but you would need to get the plastic to stay down flat which is a challenge without any core material or staples etc.

    The lamination schedule depends on the maximum unsupported area of the skin. And how structural it is going to be for the boat. Or is it a trim panel?

    I would suggest using 2x layers of heavy woven cloth with layers of chop strand between them. Without vacuum bagging the panel to squeeze the resin out, a layer of sacrificial peel ply over the top can help to consolidate the resin into the laminate and let the extra pool up on top of the peel ply. (Just an option)

    Little plastic or timber wedges are the best to help release the laminated skin from your flat surface. And leave it cure for a few days to avoid the panel warping when released. Resin can take 7-9 days to reach full cure depending on temps and humidity.

    Vinylester resin is my preferred choice of resin system. And will still allow you to use flow coat over the top.


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    1993 bermuda by Haines 530f - completed resto.
    1976 cruisecraft rogue 14 - estuary weapon.
    1984 vickers easyrider 156 - future project.

  6. #6
    Ausfish Addict Chimo's Avatar
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    Re: Making fibreglass skins

    Or you may consider using the old 3mm ply as a template and lay a sheet of melenex over the ply to work as the release agent. I would cut your sheets of glass to the size of the 3mm template and alternate resin with mekp and glass layers to get your desired thickness.Trim to size with a box cutter before the resin/glass goes off and you will have correct sized walls ready made. Rather than flick paint on the surface afterwards add about 10 % flocote to the last batch of resin mekp and you will have a coloured top.

    Have fun.
    What could go wrong.......................

  7. #7
    Ausfish Addict Chimo's Avatar
    Join Date
    Jun 2006
    Location
    Gold Coast

    Re: Making fibreglass skins

    Or you may consider using the old 3mm ply as a template and lay a sheet of melenex over the ply to work as the release agent. I would cut your sheets of glass to the size of the 3mm template and alternate resin with mekp and glass layers to get your desired thickness.Trim to size with a box cutter before the resin/glass goes off and you will have correct sized walls ready made. Rather than flick paint on the surface afterwards add about 10 % flocote to the last batch of resin mekp and you will have a coloured top.

    Have fun.

    ps https://www.google.com/search?q=meli...t=firefox-b-ab
    What could go wrong.......................

  8. #8

    Re: Making fibreglass skins

    ALM are u talking about knee and foot kick boards or side pockets or do u actually mean the sides of the boat from the gunnel to the floor? i have seen both done but most likely the first one mentioned if this is the case the side pockets can be structural but your boat is alloy so it may not be, i have a boat now that needs them replaced on my 4.5m runabout

    mine are around 15mm plywood carpeted if u were to remake this in strait composite you'll be there for a few weeks laminating and sanding between layers

  9. #9

    Re: Making fibreglass skins

    Hi, a few years ago I used aluminium sheet (works on ply as well ) covered with cling rap (works better if you 'wax' before the cling rap (the "wax" can be any sort of grease), its OK the finish on the cling rap side can get a bit "bumpy" if the cling rap is not applied smoothly (wavy lines ) make sure the cling rap covers the edges, the sheet can be tricky to release if it's wrapped around the edges. Some of the cling rap will stick to the fiberglass, especially if you have a "hot mix " that won't matter if you only want one 'good side', I am assuming you are trying to produce a flat sheet.
    Frank

  10. #10

    Re: Making fibreglass skins

    Thankyou all, some great replies and advice for me.

    They are purely cosmetic walls only, no structural use, just to seal over the ribs etc of the sides. Then paint, and just to make look pretty. I'm after a Non rotting option, with minimal weight and a reasonable strength to withstand bumps and knocks etc, some speakers and lights will be cut into them at certain areas, I will reinforce these areas with a few more layers of glass, but they shouldn't have any serious work to ever do.

    I will make and cut in some pockets after the initial skin is made,fitted and ready to go.

    I'm leaning towards plastic sheets due to the foolproof method, and not having to determine correct waxes etc. I have a 2400 x 1200 12mm chipboard sheet here doing nothing, So ill grab some builders plastic and should be ready to rock n roll.

    I can wrap plastic around the edges and staples or tack on the underneath side. Then I will lay down 3 layers of thick matt, and ill offset the matts on each layer, to cross each other. I will resin to the edges of the board, and let cure, hypothetically, after curing, I can just use a small wedge, and crack them off the board and then cut to size and shape. Does this sound like a reasonable way to approach this job ? It does not matter if the plastic sticks and stays, I can just recoat he board for the next set. I have around 4000 x 900 on either side to do, and due to varied angles and sizes, I was planning to make them in 2-3 sections anyway.

    Anyone see any issues if I stick to this plan ?

    Whats the best tool to cut cured fibreglass with ? My options/Tools available are Jigsaw, Circ Saw, 1mm disc on grinder ?

    Thankyou again, certainly takes some pressure off and chances of failure away, with your detailed replies. Glassing is new to me.

    I have added a picture of the walled area, Not a perfect shot, but you can see the existing timber rotten walls that I am redoing.
    Attached Images Attached Images

  11. #11

    Re: Making fibreglass skins

    You will be fine with your method.
    Builders plastic stapled to the sides laid smooth is no issue at all. Resin won’t stick.

    Be careful that some fibreglass is only 1100mm wide. Just check it when ordering if going for exact 1200mm panels.

    3 layers will produce something like 2mm thick.

    Don’t rule out using 4mm hardwood bracing ply resin coated with one layer either side. The resin soaks into the skin 100 % and is a sound option.

    Make sure you buy a good paddle roller or Air bubble roller. And remember to store it in acetone and clean it out well. You will need it. 4” mohair rollers and a 2L ice cream tub works well.

    No more than 1.5-2% catalyst ratio. Don’t guess, weigh your resin on a little digital scale.

    Base your resin ratios off 1.7L per kg of glass for fabrics. Most hand lay ups of chop strand may might take a little more like 1.9-2.2L. Depending how even you can roll it out.

    All three layers can go down wet on wet.


    Sent from my iPhone using Tapatalk
    Damo's dodgy boat repairs.
    1993 bermuda by Haines 530f - completed resto.
    1976 cruisecraft rogue 14 - estuary weapon.
    1984 vickers easyrider 156 - future project.

  12. #12

    Re: Making fibreglass skins

    1mm cutting discs work ok. But leave an edge a little frayed and burnt.

    But a cheap diamond disc for your grinder. Much better.


    Sent from my iPhone using Tapatalk
    Damo's dodgy boat repairs.
    1993 bermuda by Haines 530f - completed resto.
    1976 cruisecraft rogue 14 - estuary weapon.
    1984 vickers easyrider 156 - future project.

  13. #13

    Re: Making fibreglass skins

    Thanx Ripitup, something for me to consider, and initially, was what i was going to do first. Use a ply board and glass over, but i was talked into just making fibreglass skins, Now im a little in 2 minds. I will sit on it a day or 2, and go from there.

  14. #14

    Re: Making fibreglass skins

    Are you planning on painting the panels once finished (I think that's how I read it) if so, why not use gelcoat and have it all done in one go?

  15. #15

    Re: Making fibreglass skins

    If your set on it being all glass go with the heaviest chopped strand mat u can find 1100gms i think Colan Australia make possibly heavier than put a layer of double bias on the inside and outside the idea is the mat will give the bulkiness while being a very cheap filler and the double bias will give the whole lot its strength if u were just to use 2 layers of double bias with no mat it will flex a lot also use epoxy resin over polyester resin the ER is marine grade the polyester is not ER also has UV additives too

    plywood is the best filler tho its relatively cheap and it adds a lot of bulk between the fibreglass layers, that plywood u have pictured looks like the cheapest nastiest plywood u can buy for marine use it looks like D grade structural plywood which doesn't have water and boil proof glue or MR1 glue which is moisture resistant glue

    u ideally want A/A marine ply, CD Exterior grade ply, furniture grade ply with WBP or MR1 glue

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