glass print through !

Discussion in 'Fiberglass and Composite Boat Building' started by tunnels, Jan 31, 2011.

  1. tunnels

    tunnels Previous Member

    Just some pictures of interest for those that have never exsperianced serious print through from the heavy Glass Fabrics that some inexsperiaced person used when making this mould ( 47 foot power boat hull ) .
    The stitched matt would have been ok but there wasnt enough csm and or 2 mm core matt between it and the moulds surface so when the resin went hard and shrunk, like all polyesters do ! over time this is what you get or in this case i have to contend with.:confused:
    I was told the whole mould needed to be re-surfaced but when i got a little close up and personal the indentations are more visual than first thought ! .The shiner the mould the more imperfections you will see !! Carefully i went into it with a orbital sander ,usig 400 sand paper but was hard work ad very slow ,so switched to 240 and that was much better to clean the surface down to get rid of the marks and is now nice and smooth and after 1200 sanding has a semi shine with no pattern to be seen any where .
    Got to take lots a care when buffing to not heat the moulds surface as this will make the pattern reappear .
    The moulds came from Queensland Australia ( go ozzies !!! ******* !! ) and have been made for some time so have been in the ozzie heat for a few years ! I have no idea how many boats were ever taken out so should be well cured !! maybe !!.
    A good point to remember is to keep wove and stiched materials well away from the surface and if you use polyester resins remember they shrink and its a good idea to cook your mould well for 24 hours or longer when its still on the plug ! :D:p:p
    Its worth the extra to use a better resin as well even a vinylester for the first half and a poly for the rest is price is a problem . Or of you are priviliged to have Proper mould making resin in the country you are in even better . Making moulds is such a waste of materials ! The hours that are spent to get it to a moulding stage! then the mould its self and the plugs just to make a few boats .
    Then you are out side ,discarded and forgotten no one wants them !THE THINGS WE DO !!
     

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  2. brokensheer
    Joined: Jun 2009
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    Location: So. Md

    brokensheer Senior Member

    Wow, so what would you say makes a good mold surface in a laminate schedule?
     
  3. War Whoop
    Joined: Jun 2003
    Posts: 661
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    Location: Sunny Ft Lauderdale Fla

    War Whoop Senior Member

    Production Molds I am pretty traditional,Two coats tooling Gelcoat then a layer of 3/4 or 1 oz Mat, cure, then two layers the next day and so on,(barcol tester is important here) BUT always break the edges so all that goes down is ONE! since ester resins cure in cross section ,Keep everything uniform,you see laps!! Fire the guy on the spot.
     
  4. tunnels

    tunnels Previous Member

    Like Steve said its the inital layers that are the key to what you get .
    One layer of gel , the second with a little resin mixed in ,10 to 20 % resin mixed helps releases air from the gelcoat easyer and gives a smoother finish to tissue over, then a 300gram csm ,followed by a 450 gram ,each layer needs to gel and cure for a day if possible!!.
    I always try to use Vinylester resin and make sure the temprature is 20c to 25c and the humidity less than 60% and use the right catalysts for each product you use , after you have at least 900grams of csm on and really hard ,then a layer of 450 csm + 2mm or 3 mm core matt . from then on you are able to use heavy wovens or stitched glasses but leep the catalyst ratios to a minimum so theres warmth and not heat . building slow and trying to elliminate shrinkage is very important . :D:);) Also keeping overlaps out during the first part of the build just butting the glass with torn edges and no sharp sissor cut edges!!!!.:mad:
     
  5. brokensheer
    Joined: Jun 2009
    Posts: 201
    Likes: 3, Points: 18, Legacy Rep: 14
    Location: So. Md

    brokensheer Senior Member

    War Whoop , two layers of gel coat how thick is each coat?
     
  6. tunnels

    tunnels Previous Member

    Spray the first coat with a pressure pot and roll the second with a mohair roller . Thickness for the first coat .8 kilo/m2 like i have always used , with 1.5 % catalyst first coat & 2% for the second coat with the resin mixed . Strange but since i started using resin in the mix never had any problems of anysort with the gel coats .:confused:
    I have spent a lot a time in differant asian countries in recent years and used some real strange products during that time , China is no exception and they have a whole set of new issues and its interesting to see there methods and ways of doing things with what they have to use . Its like a trip back to the 1970s and 80s !, any kind of change has to be introduced gradually for them to accept it with great reluctance :eek: :D:p:p
     
  7. jiggerpro
    Joined: Sep 2007
    Posts: 179
    Likes: 8, Points: 18, Legacy Rep: 101
    Location: spain

    jiggerpro Senior Member

    I wonder if the barriercoat products like Crystic´s Barriercoat are really as effective as the manufacturer says, I find difficult to believe that what the gelcoat layer plus the skincoat vinylester layer cannot avoid .- the printhrough.- can be achieved so miraculously as advertised by just a 1mm layer of that thing that after all I believe is a poliester resin based product.

    Are those products really effective ?

    http://www.scottbader.com/composites-products-barrier.aspx
     
  8. tunnels

    tunnels Previous Member

    Barrier coats and ceramic fortified gels , and gel coats that are as hard as can be are only as good as they are used for if done properly . Its all about getting th e glass fibres away from the surface far enough so the bundles of glass dont print when the resin and get shrink . So curing everything at a reasonably high temprature fover a 24 hour peiod is vitally important !!!!
    Some of the shinyest moulds ive everseen were made with just plain polyester gel coat , but hand brushed with 6 brush strokes if the brush in both dirrections ,When hard a second coat thinned 10% with resin ,then a tissue as a back up and csm from there on out . The gel coat was so shiney you could see right into it like it had deepth !!
    The hardest gel coat i ever used had 400 grit carborunum powder in it . Used round the flanges of moulds !get mixed with tooling gel . A ordinary grinder had a hard time just scratching the surface .
    Have used the same mix for the bottoms of small boats that get pulled up on the wet sand a lot to stop them from wearing out so quickly . silica sand can be used as well as carbo powder , Man its hard stuff!!:D
     
  9. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    I sell the Nord Composites material, and have sold the ITW spraycore material. Yes, these materials do have a positive effect on surface quality. But as War Whoop said, degree of cure is VERY important. And sufficient gelcoat thickness.
     
  10. tunnels

    tunnels Previous Member

    Something very important to add== using the right ratio of catalyst AND the correct catalyst for the product and using the correct spray techneque at the right thickness .!!!not forgetting temprature, humidity ,and gel times :D

    Wish we could get your products here !!!
     
  11. War Whoop
    Joined: Jun 2003
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    Location: Sunny Ft Lauderdale Fla

    War Whoop Senior Member

    There are tech manuals on the MEKP blends for side by side comparison,I do not know if the one I had was meant for consumer use (it was given to me by a person on the inside) but it opened my eyes,you would be amazed at the difference.We eventually used a Norac with a little hydrogen to stop the initial foaming,My supplier stocked it for me ,but it let go and burned the place down, they did not have a refrigerated Peroxide store area. They do now!
     
  12. tunnels

    tunnels Previous Member

    Yeah i know what ya mean !!
    Catalyst in nz is treated like a exspolsive and handled with kid gloves and stored away in concrete bunkers away from everything !!
    Here in Asian countires it supplied in trucks in 20 litre containers alone with cobalt in the same sized containers and they are stored anywhere, like side by side as in against each other!!
    Catalyst is in open plastic pots laying all over the factory, in things on things and even underthings !!, when its spilt its just left to soak into the concrete or maybe cleaned up ,sort of , No one give a damn about it !!
    Was the same in Korea as well . Our unpromoted resin arrived in 4 gallon tins and a bottle sort of measured to the right quantity came with each tin , just open pour in the tin , cap the tin and shake a lot then use . the tins were used as containers to laminate with and the bottles just dumped . can imagine what the stack was like when a truck dropped off a months supply of resin and bottles .Tins of resin were handy to use as weights to hold things down and in place while glues went hard and the like .
    Had fast brews, slow brews, and the occassional brews that didnt go off at all if one the newbies was getting the resin tins in a hurry !!
    Made it the responsability of one person when working on a big job to do all the mixing all the time Cobalt and the catalyzing ! That sorted the problem once and for all .
    Its a barrel of laughs working away from the well organized and strictly controlled enviroment of every day civilized life in a real normal glass shop .
    People look at me like im crazy when i talk about these things at home !!.
    Makes ya hair curl and ya go a little grayer with each passing day !!
    Even remember having a fire inspector telling us once you can use catalyst to light your Bar b Que with it !!, Never tried it and dont ever want to , worst burn i ever had was catalyst burn when i was a newbie , I held a chunk of ice in between my fingers for a whole day to stop the pain , and the skin sore and completely white and lifeless when it stopped hurting a week later . So had great respect after that !!
    Life is a laugh a minute working as a glass person any where in this world .:D:p:p
    Tahiti was even more interesting .
    The 44 gallon drums were promoted with cobalt by the Resin supplyer and when i went to pick up a drum the guy opened the drum and just poured in what he thought was cool !!, Like how many glugs of cobalt you want ??, and to mix it was rolled round the yard a while and then loaded on the truck and got a further shacking mix up on the way back to the factory .We had a venus chopper gun there and each drum had to be opened and pumped and then a sample taken for testing to establish the gel time because it was differant from what the last drum was .I asked one day what was the resin they were using , The supplyer said it can from Holland and had no idea what it was meant to be used for . had no specs of any sort or marking on the drums . Had vertually no thixotriphix properties at all and was ok if the objects were flat but on t vertical surface it ran to the lowest point so one of the ladies here sat with a mohair roller and mopped up the runoff and put it back up top till the resin gelled .and then cleaned out the roller for next time .
    Joking aside and looking back , with all this **** that the ordinaly person would have simply walked away from the Tahtian guys were the best laminators i have ever worked with . There workmanship i have never seen equalled anywhere in the places i have worked since ,There gel coating wet on wet using multi colors was Faultless in every way , they wasted nothing!! Even grinding discs were washed with acetone and use over and over again till they smoked and caught fire !. If you cut a piece of wood the waste never hit the floor there was a hand waiting for it .
    I went there to advise and show a better way but it was me that was learning and they were teaching me .
    One laminating roller to roll glass with ,started by one guy at one end and then handed to the next guy and then to the next till the job was finished . They smiled and sang songs all day long and after a good grind up and covered in grinding dust simply ran to the end of the pier and dived into the lagoon for a swim and most ever one else joined in just for the hell of it . The trees round the yard had fruit and we all shared every thing . Life is rich and full if you let it be !!
     
  13. wrbowcal
    Joined: Apr 2010
    Posts: 38
    Likes: 2, Points: 0, Legacy Rep: 16
    Location: Crowsnest pass, Alberta

    wrbowcal Junior Member

    Thanks for this post after reading it I jumped in my truck put the peddle to the wood and headed to the shop 2hrs ago and moved my 8lb jug of MEKP from under the overhead cat heater on the bench to the fridge.I had the emergency lights on.Thats it I am writing up a check list before leave the shop from now on.
     
  14. jiggerpro
    Joined: Sep 2007
    Posts: 179
    Likes: 8, Points: 18, Legacy Rep: 101
    Location: spain

    jiggerpro Senior Member

    Some of those barriercoats work by foaming a bit producing a cushion between the skincoat and the laminate which does not sound very appealing to me since foaming means tiny bubbles that could fill with water if under the waterline which is precisely waht we do not want since what we desire is an "as solid plastic as possible" watershield, I believe that resin products manufacturers just want to sell whatever stuff that is profitable so we end users have to be careful with our choices
     

  15. tunnels

    tunnels Previous Member

    Good boy Steve !! WE do become a little complacent at times !.:D
    Its interesting to read about Barrier coats and how they do what they are supposed work , like i said it works well when it done properly and everything is set how i got to be . So the barrier coat does what the 2 mm core matt does in protecting the Gel coat from the Glass behind and the resin shrinkage !! Can some one post some real technical stuff and some pictures in super close up of the cross section of Barrier coat .
    This is interesting stuff and am sure theres others would like to see the same info !
    As for the water in the gel coat just do the topsides and not the bottom Same with Core matt Never use below the chine line !!
    !:p
     
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