plug stuck in the mold

Discussion in 'Boatbuilding' started by Trick Powerboats, Feb 2, 2013.

  1. Trick Powerboats
    Joined: Apr 2008
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    Trick Powerboats Junior Member

    How long should we wait to spray the gelcoat after spraying the pva?

    Jeff
     
  2. tunnels

    tunnels Previous Member

    As soon as all the pva is dry to the touch gel coat it .
    Now think just a little here , one night or day of high humidity and the pva will be damp and if its damp how will that affect the gel coat ?? what will the moisture do ???? come on your not thinking !!!:eek:
     
  3. groper
    Joined: Jun 2011
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    groper Senior Member

    same here, as soon as it looses the wet look, i start working... about 5 mins or so...
     
  4. midnitmike
    Joined: Apr 2012
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    midnitmike Senior Member

    Jeff,
    Hopefully you're going to take some of the suggestions posted here seriously and determine for yourself the best possible application techniques. I stumbled across this page a few years ago...you might find it interesting.

    http://winshipmodels.tripod.com/pva_mold_release.htm

    MM
     
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  5. groper
    Joined: Jun 2011
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    groper Senior Member

    As quoted by the author of that article "no pVA is better than thin PVA" i dont agree with... ive tried thick coats of PVA and thin, ive noticed no appreciable difference in the release.

    The main difference ive noticed, is that the finished part is more likely to have a better surface finish when only a thin coat of PVA is used...
     
  6. tunnels

    tunnels Previous Member

    This Is Like Teaching In A Kids Kindy

    To make sure its dry blow dry air across the surface and dry your hand in the air stream and everso gently brush you hand lightly over the surface and if theres no sign of any sort that you have wiped you hand its dry,Just remeber you hand has sweat glands and if you stop the moisture from you skin will disolve the PVA !! You can do this also to gently wipe any dust off the surface as well .

    Have much exsperiance do you have spraying gel coat ???
    what sort of equipment have you got ???
    is it a pressure pot or a bigger unit ??
    Me I preffer to use a pressure pot but keep the air line pressure down to about the 50 psi mark !!!
    I always make and set up my own pressure pot spray units so i know what its completely capable of and what adjustments i have to get the best flow , the best possible atomisation of the gel coat ,to get the best possible even coverage and a constant thickness all over !!!.
    When spraying a big job with a pressure pot you need to have 2 other people with you !,(one person does all the mixing no one else ) one person to mix the gel coat the same each time !!most important !!
    the second guy to fetch and carry the pot disconnect etc etc and the third person doing the spraying so he can 100% concentrate of what he is doing !!!

    Each company i been working in i have made a pressure pot unit and they are always the same . Usually i collect all sorts of old bits that are laying around the shop to make each unit and just buy two small new regulators and what ever else is missing usually finding the right type of white plasitc supply hose from the pot to the gun is the hardest thing to find .

    Any way get on with it and think and make the best job possible!! :D
     
  7. tunnels

    tunnels Previous Member

    Look and learn !!

    That was a very interesting artical and the best explination ive ever read to date .
    I to agree thin is better than thick and yes its possible to get a good shine with thin PVA its the reason i thin up to 60% with just plain tap water so the thin becomes even thinner . Like all and every process devised and used everywhere there are small tricks we all use and makes things work even better .
    From the time Fred showed me (1985 ) till now i have never changed the formular of water to PVA and not really changed the air spray and drying method .
    Its most important to have dry air in the glass shop !! for spraying or the use of any type of air tools moisture in the air line is a reall problem !!As a precaution i always use big dia lines and a secondary water separator /filter in the line before the connection i plug into .

    If you cover all the possible causes of silly problems jobs go smoothly and problems are for other people to have !! not yourself .

    Just about all the products such as wax's need to gas off into the air so a gental flow of air blown across the surface with a pedistal houehold fan speeds up the drying /gassing off process and wax's dont have to be left for hours and hours between coats .

    That was interesting that one coat of wax or 20 coats of wax , the wax thickness hardly changes and you never build thickness !!! just waste time and waste product !
    Confirmed what i was told years ago by a old guy i worked with !
    So a light application with a soft damp sponge ,well rubbed holds true .

    Again i learned from watching others years ago when i firststarted in the industry and taking particular note of who made what work the best and what was there methods they use . :idea:
     
  8. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    There doesn't look to be any draft to the plug, but there could be, it's hard to tell. Are all those sharp edges left after you finished the plug?

    [​IMG]

    I never understand why anyone ever has to wet sand a mold after removal from a plug. To buff it and polish it up is OK, but if you have to wet sand a new mold, you've done it wrong.

    Aside from all the advice on PVA etc, when laminates cure, they shrink. So if you use hot or even normal production catylization ratios, you add to the problem when making a mold that encapsulates a plug. You should go slow and allow laminations to cure before putting on more, like tooling gel, allow to cure, then a 3/4 oz mat, allowed to cure, then a 1 1/2 oz mat allowed to cure, then another allowed to cure, then maybe two 1 1/2 oz mats, etc.

    There sure doesn't look to be any draft on that plug though.
     
  9. tunnels

    tunnels Previous Member

    Who said he was a plug maker ?? hes a fruit cake manufacurer !

    Is that the console plug we been talking about they had trouble getting apart ??
    Who ever built it has never made plugs to take mould off thats for sure . its terrible !! .
    Can you imagion making shape inside a mould if it got that far !! no rounds !!sharp corners !!you will have glass pulling and drawing and changing the shape of the artical on every panel , after a years in use it will look horrible !! yuk !!!:confused::eek::mad::(
     
  10. tunnels

    tunnels Previous Member

    I really think you should post some pictures of the hull plug and the deck to see what you have got
     
  11. Trick Powerboats
    Joined: Apr 2008
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    Trick Powerboats Junior Member

    Slow down there guys. I've been building boats for 10 years and I've built my fair share of molds. So this aint my first rodeo. But I'm quite sure that many of you have forgotten more than I know. But like many builders I've been building the same stuff over and over so I occasionally run into things outside my normal routine. Now I'm working over seas and things that I took for granted at home just arent available here.

    That picture of the seat that you're talking about is what the seat looked like two days into the plug building process. I fully understand draft and radius and how they affect the release of parts.

    I really appreciate your responses and help but don't make too many assumptions.

    Jeff
     
  12. waikikin
    Joined: Jan 2006
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    waikikin Senior Member

    A few years ago
    i was using a 200mm pvc pipe to make some gelcoated inside corner molds, the stuff was very "reactive" & grabbed through the wax & PVA, ended up I shot it 6-8 times with PVA & worked great & nice gloss blah blah, some times molds are CraBBy & PVA will improve the finish. Jeff.
     
  13. Trick Powerboats
    Joined: Apr 2008
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    Trick Powerboats Junior Member

    We've removed the plugs. The molds are perfect with the exception of a couple of scratches we made removing the mdf.
     

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  14. Trick Powerboats
    Joined: Apr 2008
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    Trick Powerboats Junior Member

    Here is a pic of the hull side after duratec and sanding.
     

    Attached Files:


  15. waikikin
    Joined: Jan 2006
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    waikikin Senior Member

    Nice Mate
     
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