infusion media questions

Discussion in 'Materials' started by JohnMarc, Feb 14, 2020.

  1. Chris Rogers
    Joined: Apr 2020
    Posts: 25
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    Location: Boston, MA

    Chris Rogers Junior Member

    Looks like you have a good process and I agree with all of Andrew's advice. Sometimes when you have small flanges you can put your resin break (spiral wrap wrapped in peel ply) up in a pleat of bag along the edge(s). It makes the bag bigger but can give you a few inches of slow flow to help everything fill. Looks like you have enough room to sneak the vacuum-side tube closer to the sealant tape.

    I wrote up a post about troubleshooting vacuum infusion - some parts of it may be useful.
    Troubleshooting Vacuum Infusion | Explore Composites! https://explorecomposites.com/2019/11/19/troubleshooting-vacuum-infusion/

    Interested to see how it comes out!
     
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  2. AndrewK
    Joined: Mar 2007
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    Location: Australia

    AndrewK Senior Member

    Chris, I like your trick for extending the resin break into a pleat.
    Also just read your write up, I think it is great. Well done.

    A trick that is not mentioned in you write up that I use to see if I have micro leaks or moisture in the laminate is to put the pump outlet into a clear container with just enough water (use oil if you prefer) to cover the hose. If all good there will be no bubbles.
     
  3. JohnMarc
    Joined: Feb 2018
    Posts: 128
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    Location: Knysna South Africa

    JohnMarc <--- My ultimate goal

    Hi Chris
    Many thanks for that, good article well written.......
    I have demoulded and if I say so myself not bad at all thanks to all the good advice.......doing a clean up after which will post pic....... couple of things I noticed during the infusion process bothered me, some of which the article answered.....ie. air bubbles seeming appearing from nowhere....
    What I noticed happening was that the resin naturally takes the path of least resistance resulting in quite a bit of the resin flowing down the "Bead" around the edge and ending up in my catch pot while waiting for the rest of the infusion to catch up. I hope the attached pictures explain my issue .....I was wondering wether there is a way to slow down the resin flow in areas like the bead that offer a path of less resistance, has anyone else had similar issues and found a way to slow down the flow in selected areas.

    Screenshot 2020-04-17 at 11.22.03.png Screenshot 2020-04-17 at 13.21.46.png Screenshot 2020-04-17 at 11.22.31.png
     
  4. AndrewK
    Joined: Mar 2007
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    Location: Australia

    AndrewK Senior Member

    John, you must have had bridging over your bead area. This can also happen around core edges, to minimize this apply initial pull down vacuum in stages. When it gets to just before the bag pulls down massage your reinforcement and mesh into this area then apply bit more vacuum to the first point of clamping and repeat. Look and feel for this bridging only when eliminated apply full vacuum. This is where shade cloth being a knitted material has advantage over plastic mesh as it drapes a lot better.
    Secondly this is why you want larger resin breaks, the resin that raced around your bead area and hit the break it would have greatly slowed down allowing the rest of the infusion to catch up.
    Thirdly when you anticipate potential fast tracking or you simply have uneven distances to infuse break down the vacuum line into segments with 50 to 100mm gaps. This allows you to temporarily close off the sections that fill first. So not only does the resin break give you time for the slower/bigger sections to catch up but you will also have the resin move sideways towards the vacuum line from the sections already filled. When it all evens up and infusion finished open up all of the vacuum sections again. Always plan to have a big enough resin breaks so that no resin gets into the vacuum lines.
     
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  5. JohnMarc
    Joined: Feb 2018
    Posts: 128
    Likes: 7, Points: 18
    Location: Knysna South Africa

    JohnMarc <--- My ultimate goal

    Ha ha just had a closer look at some of the picture and videos I took of the process and reading your very first suggestion you were spot on. I took care to ensure the bag was settled in the beading all around but for some or another reason I missed the bead on the vertical side which had a crease from the pleat running almost all the way down the (short) length of the mould along the bead, hence my "river" of resin......
    Got a further "problem" two of my friends with the same vehicle have asked for these hatches as well.....so going to be doing this a few more times..... I am wondering if I might be better off doing the vac line all the way round and feeding the resin from a short line in the centre. I am quite happy with the result I got (being the first time for me with a "complex" mould like this) but I do want to experiment with different methods. All in preparation for building my boat.....
    Then if I may, one final question..... I have some damage along the bead where some of the gelcoat stayed behind in the mould....my waxing obviously was not thorough enough..... my question is can I thicken some gelcoat and repair it with that. I do not want to go the body filler route as I think this "window" will be prone to some pretty harsh vibrations and extremes in exposure to heat and cold (deserts and high mountains) and worry about a repair not bonding as well as I imagine the gelcoat would.

    final.jpg blow out gelcoat.jpg
     
  6. AndrewK
    Joined: Mar 2007
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    Location: Australia

    AndrewK Senior Member

    You are going to paint the hatch so I would just use body filler.

    Might as well experiment while you can, I would actually do reverse, perimeter feed and vacuum point in the center of the hatch cover.
     
  7. Dejay
    Joined: Mar 2018
    Posts: 611
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    Location: Europe

    Dejay Senior Newbie

    "I have some damage along the bead where some of the gelcoat stayed behind in the mould"

    Can't you peel the piece out of the mold and glue it back in?

    Looks really nice! Thanks for sharing your project!
     
  8. JohnMarc
    Joined: Feb 2018
    Posts: 128
    Likes: 7, Points: 18
    Location: Knysna South Africa

    JohnMarc <--- My ultimate goal

    Hi Dejay..... sometimes the simplest solution is an obvious one...... why didn't I think of that.....yes of course will do just that.

    Thanks
    Stay Safe & Healthy
     

  9. Dejay
    Joined: Mar 2018
    Posts: 611
    Likes: 113, Points: 43
    Location: Europe

    Dejay Senior Newbie

    Haha glad I could help :)
     
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