plug stuck in the mold

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

  1. tunnels

    tunnels Previous Member

    Nice picture or a piece ot a mould but how about a wide shot . Dura tech sure can clean up nice !!!
    The console looks pretty ok But id sure as hell be PVA ing it from one end to the other including the flangs and the outside of the mould !! yip the very outside !I hate working with grubby moulds specially new ones !!
    Sorry we all jumped but wanr getting to many good vibrations in some of the questions being asked !!. will reserve comments till later !! Good luck !:D
  2. Trick Powerboats
    Joined: Apr 2008
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    Location: Al Raha Beach

    Trick Powerboats Junior Member

    "who said he's a plug maker, he's a fruitcake maker!" Screw you buddy! Who are you to judge me or my work without ever seeing one thing I've ever built. So I stuck a plug in a mold, who hasn't? That kind of comment is totally uncalled for, unprofessional and ignorant.

  3. tunnels

    tunnels Previous Member

    Ooops touchy as well !

    Lack of response and information or the wording of posts leaves one to wonder ! all points to the negitive ! have a nice day !!:D
  4. midnitmike
    Joined: Apr 2012
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    midnitmike Senior Member

    I think what the study points out is that an improperly applied PVA coat (ie. too thin) can cause hazing of a fresh mold surface. This hazing can then affect future part production from that mold. The whole idea is to create an inert mold surface and properly prepare the mold for it's production cycle. What I came away with when I first read the material is that sticking a part is NOT an uncommon phenomenon. It happens industry wide irregardless of the shop, personel, or experience!

    I'll agree that a correctly applied coat of PVA can and will produce a finer surface finish then one that's been mopped argument there. Where I will continue to advocate for heavier PVA coatings is when we're advising posters of unknown experience or where they have already stuck a part. A stuck part can be indicitive of improper mold preparation, and if the mold surface is still in a reactive stage then their only recourse is to procede with caution. Once the mold has been properly initialized then wax alone is adequate mold release, but until you get two or three parts out of the mold you should always error to the side of caution.

  5. keith66
    Joined: Sep 2007
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    Location: Essex UK

    keith66 Senior Member

    Last year i built an interior moulding for a rowing skiff, mdf plug built inside the hull then sprayed with durabuild & worked on for a lot of hours. I used honey wax & gave it at least 10 coats, sprayed with pva & applied the gel.
    I used vinylester tooling gel & vinylester skin coat followed by tooling resin.
    Guess what the mould stuck to that plug like **** to a blanket.
    I had to destroy the plug itself to save the mould but as it happened there was very little damage. I am 99% sure that the reason it hung up was that the temperature when applying the tooling gel was too cold, it was wintertime & i didnt have enough heat in the workshop, the longer cure gave it time for the styrene to eat into the plug surface.
    Once that mould was polished & waxed i pva'd it & gave it a break in gel coat that i ripped of as soon as it had cured. It came of fine & after 5 more wax's & pva the first molding popped of with ease.
    It was a scary lesson & in future i will always try a test piece on the plug to check it will release. Plus break in the mould, better waste a gallon or so of gel than lose a moulding plus mould!
    1 person likes this.
  6. tunnels

    tunnels Previous Member

    Do you know what your gel time was ??

    All through just about every post i nearly always state, temprature and humidity along with making a small test sample and checking the gel time !!!
    Also using the correct Catalyst stated by the manufacture and the percentage recomended ,along with proper mixing and method of application !.And NEVER thinning your gelcoat with anything especially styrene !! . styene is the worse product to thin any gel coat with as its the styrene that attacks the wax and the pva and if it was cold and the gel time was longer than it should have been you got what you got !! a massive stick up !!.
    No two catalysts are the same ,theres a list great long list of catalysts and each one differs .
    Catalysts used for gel coats normally produces less gas during its reactive time and there for smaller bubbles but only if its used as is recomended by the manufacturer . if you have a look at any spec sheet for any products testing is carried out at a baseline of say 25c and thats where i performs at its best .
    Some gel slowly WITH long work time and then cure quickly , others gel quickly but have long cure times and even to the point of warming the finished product for a few hours to achieve its hardness.
    working at below the recomended temprature and not knowing what the humidity % was is just asking for troubles, and you got them !
    Making plugs and making moulds as is seen is a little hit and miss and there are many reasons for moulding sticking .,even to the point of the base paints used during there making !!
    Durtech is the only product i will use for the finish on plugs as its almost fool proof , shines well , gives a hard finish , 2 coat of floor wax, thin coats well rubbed and a fine thinned PVA sprayed and dried with dry air and never fails .
    As also has been stated not only by myself but others 10 coats of wax or 20 coats of wax makes very little to no differance to the thickness after the first 1 or 2 applications of wax . Honey wax, mirror glaze, even TR wax has little baring !!
    NO YOU CANNOT BUILD THICKNESS EVEN WITH 100 COATS OF WAX!! thats a myth we all get told the day we start working in a glass shop !
    In most recent times the good old johnsons floor wax wins hands down over any of the other waxes .
    I have my method of applying a watered down thin coat of pva and since 1985 have never had the hint of a plug or mould hang up , and in production where products have been difficult to release and remove a thin spray of pve has cured that problem and the product comes out 99.9% clean and after a hose off shows no signs of ever having pva used , has a good finish and neve had a hazy or non glossy finish . :p

    REMEMBER its not the product thats at fault its the person using the product !
    90%of failures are poor workmanship or lack of understanding of the products being used
    the other 10% is bad choice of materials !
    This was posted by midnightmike and is really worth reading and taking the time to reflect of each point of waxing and use of pva
  7. groper
    Joined: Jun 2011
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    Location: australia

    groper Senior Member

    My experience tells me, if you have a new mold or plug, never brush the gel coat only spray it... most of my stick ups occured when brushing the first coat on the PVA which can ruin it IMHO...
  8. tunnels

    tunnels Previous Member

    Like i said years ago we never used pva , years ago we always brushed Gelcoats or what ever ,some where in the 1980s and after we started to see lots differant products arriving on our markets and the troubles began . Was also about that time i got into spraying Pva (1985)was some where in that era tooling gels must have changed and people began getting some really bad stick ups .
    The tooling gelcoats dont seem to be compatable with any of the waxes that we use any more for what ever reason , like i said a few posts back if you spray it seems to be 90% ok but if you going to brush forget it !!. Could simply not use toolong gel coat any more !!. I havent used tooling Gell since Korea in 2008 and that was touch and go on some small itams that were brushed with the same gelcoat as we had sprayed with . :D
  9. keith66
    Joined: Sep 2007
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    Location: Essex UK

    keith66 Senior Member

    Guilty as charged your honour! Luckily i got away with my stick up.
    Humidity was under 65% temp was too cold at 16 degrees c
    I would add that its easy to get the air temperature of the workshop up but the surface that is being gelled should be up to the same temperature, thats where i fell down!
    As an aside, a few years ago i saw a big cat being laid up in a polytunnel in the middle of winter, they used several big diesel space heaters, there was condensation running down the walls & dripping from the ceiling big time, it came out looking ok but i am surprised they got away with it!
  10. tunnels

    tunnels Previous Member

    Thats something people and companies dont even consider is the moulds and everything associated to the temprature the whole deal needs to be warmed and been warmed for at least 6 to 12 hours before the job starts . spraying onto a cold and even humidity dampened mould is an instant killer that no one sees and another of the mystries of "WHY DID THAT HAPPEN" ??
    product in a 20 litre drum needS to up on a work bench or some where and not siting on the cold concrete floor stuck in the corner of a workshop with concrete or steel walls ,takes almost 24 hours for the whole of a 20 litre container to get to close to room temprature !!,Not many people even consider these things !!
    Keep all and everything up off the floor a humle wooden pallet or two with a ply sheet on top is a good place to sit all and everything including all your gear .
    Have you ever sprayed hot gel coat ??
    We used to make spa pools and they get osmosis in hours of being used so the gel coat was a special and had to be sprayed hot and multi coats one after the other to get the thickness right Vow it was nice stuff to spray . Used a venus gel coater with a line heater and was like enamal paint with a brilliant shine The pools that we used it on just looked like the others and never had problems .
    Tell you another thing while i remember the size of you airlines is another cause for concern . As a main flow line run over a distance i always have a 1/2 inch line with a small manifold of about 6 take off points this is the main fed and has a built in water separator filter at the wall end . Then the lines reduce to 3/8 high flow fittings this reduces the risk of a restriction point and temprature drop in the lines and the air supply at the gun is much better and dry !
    I watched with a smile while visiting a company a guy trying to understand why his airline was spitting and had a stready stream of water mist coming out the end ! he was about to spray gel coat !!

    Have fun :)
  11. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    The thing with Johnson's Paste Wax, or whatever it's called, was it was 100% Carnuba wax. If they ever change the formula, problems might develop.

    In the early 80s I used to get my materials from the We-No-Nah Canoe Co in Winona, Minnesota. Their system for heat was infrared heating that heated things and not the air. It was odd in the winter to have a cool air temp in the factory but rolls of glass, molds etc were warm to the touch. I do wonder what the health effects of that are though, it seems like you would be being radiated or slowly microwaved.
  12. tunnels

    tunnels Previous Member

    The foor wax has smelt the same since i was a kid ! its seems its never ever changed, buts is packaged and sold by fibreglass companies with differant names .
    In nz it also goes by the name of TRAFFIC WAX but is pink colored . it was used as release wax but for a company doing resin injection moulding with two piece water heated aliminium moulds !!
    It smelt and felt the same but because of the coloure i wouldnt use on a glass mould incase of pink colour transfer to the gelcoat on the product .

    The heat lamp thing is a dangerous one its localised surface heating and not a good idea , My auto body repair and car painter friend uses them for paint repairs and touch ups etc but its not for glass work .

    Working inside a 100% tented area is the way to go . make it and maintain a constant controlled enviroment with an air conditioner unit mounted on a unit with wheels and works fine! low humidity ,warmed air ,comfortable and everything is completely predictable Gell times stay the same and never change if you use the same ratio all the time ,cure time is predictable !,gel coat does what it surposed to do and problems dont happen .
    Theres a bubble material with a sheet each side and makes really good tents and is very efficent at retaining warmth so its not lost to easly . its amazing how much moisture and damp and cold comes from a floor or concrete walls . so plastic the floor first and cover with old cardboard boxes opened out and tapped together , a couple of layers of Corrigated cardboard wrap is good , sure will flatten where you walking but thats only a small area .
    The more you insulate the easyer to get warm and the long it will stay warm !!
    Theres temprature controls on aircon units and there even temp controlled switchs you can get for you power leads .
    Also remember as you finish you jobs put the all resin containers outside away some well away in case of brews left and getting hot .
    its peace of mind and takes the worry and hassles out of making products .

  13. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    I don't know if someone else mentioned heat lamps, but I was talking infrared heating, where the heaters were on the ceilings 10-15 feet away from the floor. You didn't feel any heat directly, like something you could warm your hands over, but things were warm. Like this system...


    Here's another place with a better description of the systems.
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