first time using fiberglass, seeking advice

Discussion in 'All Things Boats & Boating' started by Conundrum_UK, Jan 15, 2010.

  1. hoytedow
    Joined: Sep 2009
    Posts: 5,857
    Likes: 400, Points: 93, Legacy Rep: 2489
    Location: Control Group

    hoytedow Carbon Based Life Form

    Conundrum, the view ports on the front of the costume may be available through your local optometrist. They sometimes have circular convex lens samples showing the different shades available. You may be able to persuade them to part with a few obsolete shades. They are typically in the 7cm diam. size.
     
  2. apex1

    apex1 Guest

    Build the "Metal" parts of cheap glassfibre, even mat will do, and polyester resin. Use a light fabric, say 100gsm for the visor part of the helmet. Make the layup on a film of "mylar" and you have a clear transparent screen you can look through! The glassfibre becomes transparent when saturated with clear resin.

    You can use any light polyester fabric reinforced by cheap polyester resin to make the rest of the costume.

    Hope that helps.
    Richard
     
  3. Conundrum_UK

    Conundrum_UK Guest

    Thanks both of you, I'll check about the optometrist sample lenses & get the materials ordered in the next few days :D
    I've heard that epoxy is stronger than polyester, I don't mind paying extra for a better strength / weight ratio even if it doesn't really need it (like I say, I like to overengineer for durability). Would it give an advantage? or would I be better just using extra layers of polyester?
     
  4. Frosty

    Frosty Previous Member

    If you are a thespian you would get a discount from a theatrical shop. I think there is a good one in the high street in Basingstoke near the Tahj Mahal Indian.

    If you dipped your jammies in epoxy and then went to sleep, in the morning it would be stiff.
     
  5. apex1

    apex1 Guest

    Epoxy becomes inert when cured, poly not to the same extend. So, epoxy is the better choice, yes. And a bit stronger too.
     
  6. Conundrum_UK

    Conundrum_UK Guest

    OK, thanks yet again for the information, just about to order the materials, so far decided on the SP 106 Multi purpose Epoxy - 3.02 KG Pack - Slow @ £48.95 that I was looking at before, It seems as though the cheapest cloth available is: 450g Biaxial cloth - 1.27 mt wide £2.98 per meter
    I take it there's a 1:1 ratio of cloth to resin? so if I get enough of this for 1 layer and maybe add a less itchy, lightwieght cloth like polycotton for an inner layer, would it be likely to need any more layers for the main body section? Not sure about the impact resistance of biaxial vs woven. I'm probably just getting paranoid about this but it's a big project for me.
    The complete costume should be about 6-7ft tall, but the main body is about 42" of that, surface area around 3 square meters.
     
  7. apex1

    apex1 Guest

    The 450gsm is already a bit overkill, I would say. But when it shall last forever...300 does it!
    The prices are fair!
    Yes the weight of resin and fabric are more or less equal, when you wet out the fabric proper (and not overdo the job, more does´nt help more)

    So, when it comes out at 3m² you would end up at about 3kg weight, still much.

    Regards
    Richard
     
    Last edited by a moderator: Jan 18, 2010
  8. Conundrum_UK

    Conundrum_UK Guest

    :confused: sorry for bumping an old thread, but I'm just about to start fiberglassing the mold and there's something I wanted to check. I'm using a slow curing epoxy and the leaflet says it should be used at a temperature of 15-25 degrees centigrade. The room I'll be using though isn't heated or insulated and the temperature doesn't go above 10 in the day. At night I don't know if it's even above 0. Is this likely to be a problem?

    Also, this is the male mold I've made so far
    http://i45.tinypic.com/29473pf.jpg
    (The photo actually shows 2 molds, the larger one for the body shell, and the smaller dome shape for a removable helmet that slots into the front)
    my plan so far is to cover it with a thin pvc sheet, stretched tight around it, to act as a release agent. It doesn't matter if it gets stuck to the fiberglass because then it's a barrier between the fiberglass and me, as long as it doesn't get stuck to the mold. In order to not destroy the mold though, I plan on fiberglassing the left half first (the right half is visible in the photo), removing it after curing, then doing the right half, then joining them together with an extra layer down the middle. I've heard that using multiple layers after curing is bad, but the only alternative seems to be to destroy the mold, which I'd prefer not to do. Any advice?

    Thanks again in advance.
     
  9. hoytedow
    Joined: Sep 2009
    Posts: 5,857
    Likes: 400, Points: 93, Legacy Rep: 2489
    Location: Control Group

    hoytedow Carbon Based Life Form

    Can you put a space heater in the room? You really need it to be sufficiently warm to get a good cure. If you can have the heat warming one side of the room where the epoxy is curing, that should be adequate. You don't have to get the whole room warm. Directional heat should do it. Place a couple of thermometers in strategic locations and monitor them. No open flames!
     
  10. Conundrum_UK

    Conundrum_UK Guest

    I have access to a small electric space heater, but I've done a bit of testing with it and it doesn't seem to be able to cover the whole area of the mold I'll be working on. I'll try and find another heater, thanks for letting me know.
     
  11. Conundrum_UK

    Conundrum_UK Guest

    I'm not sure why, but this isn't working. I tried a test piece about A4 size, measured out 100ml of resin to 20ml of slow hardener (the mix ratio is 5:1), gave it what seemed to be an excessive amount of mixing, then spread it on as evenly as I could. I left the sample with a hot water bottle underneath it and a space heater shining on it for most of the day, then switched everything off and went to bed. By that time it seemed hard in that it clicked when I tapped it with a fingernail.

    I picked it up this morning, this is what I found:
    [​IMG]

    The whole thing is flexible, as if I used rubber instead of epoxy. I'm not sure what would have caused this. Is there any known problem that causes results like this? I really need this stuf to be loadbearing when I make the finished shell. Any ideas?
     
  12. hoytedow
    Joined: Sep 2009
    Posts: 5,857
    Likes: 400, Points: 93, Legacy Rep: 2489
    Location: Control Group

    hoytedow Carbon Based Life Form

    What temperature was the room?
     
  13. Conundrum_UK

    Conundrum_UK Guest

    it varied between nearly 20 degrees when I had both the heaters running to about 5 during the night, They were only kept at full power for about an hour though then turned down. The sample had, I think, most of the day at 15 degrees or more (though it may have dipped below that on a couple of occasions).

    It looks like temperature was the problem though, I left that sample on a couple of hot water bottles by the radiator yesterday and now it's much stiffer and stronger. I guess it hadn't fully cured yesterday morning.

    Anyway, sorry to dig up this thread again unnecessarily, guess I'll have to find some way to increase the temperature for the next batch.
     
  14. Herman
    Joined: Oct 2004
    Posts: 1,618
    Likes: 94, Points: 48, Legacy Rep: 1240
    Location: The Netherlands

    Herman Senior Member

    Indeed. You cannot expect slow curing epoxy to completely cure overnight at 15 to 20 degrees C. It just needs more time, or more heat. Even when heating it up to 80 degrees C it needs time to fully cure. (I deliberately do not give an exact time, as I do not know which epoxy is used.)

    Also, keep in mind that the 100:20 mixing ratio very probably is by weight, not by volume. With the hardeners typically being lightweight, and the resin considerably heavier, you can be as much as 15% off (meaning the weight ratio is 100:17 instead of 100:20.

    In general, this should not have too much influence on cure time. The cured resin might be a bit on the stiff side. Adding more hardener than neccesay makes it a bit more on the ductile side. Still, I would aim for the most exact ratio as possible.
     

  15. hoytedow
    Joined: Sep 2009
    Posts: 5,857
    Likes: 400, Points: 93, Legacy Rep: 2489
    Location: Control Group

    hoytedow Carbon Based Life Form

    Please keep us posted as we want to see how your project turns out. Good luck.:)
     
Loading...
Similar Threads
  1. SuenosAzules
    Replies:
    4
    Views:
    2,305
  2. Squidly-Diddly
    Replies:
    10
    Views:
    2,361
  3. Corley
    Replies:
    1
    Views:
    1,560
  4. Squidly-Diddly
    Replies:
    54
    Views:
    11,148
  5. Frosty
    Replies:
    12
    Views:
    5,021
  6. BBill
    Replies:
    4
    Views:
    412
  7. Ike
    Replies:
    20
    Views:
    4,491
  8. JosephT
    Replies:
    6
    Views:
    2,064
  9. D Coleman
    Replies:
    1
    Views:
    1,265
  10. dollerprod2
    Replies:
    5
    Views:
    2,778
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.