infusing with contour balsa

Discussion in 'Fiberglass and Composite Boat Building' started by Steve W, Jan 9, 2014.

  1. AndrewK
    Joined: Mar 2007
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    AndrewK Senior Member

    We get the polyester tafata for $1.25m2 from the fabric wholesaler. Shade cloth is knitted which provides the resin channels, I can take a close up photo if you like. 30% consumes 320g/m2 of resin, the 50% shade consumes 500g but is almost twice as fast. 30% shade cloth costs $1.70m2 and 50% $2.45m2 compared to infusion mesh $5-10m2.
    50% shade cloth is similar to Greenflow mesh in performance.
    With the luxury of long gel time with epoxy I use 30% shade cloth to keep the consumables cost down. But only infuse with transfer matt when trying to keep the weight down to minimum, otherwise the grooved and perforated core is much simpler to use.
    My recommendation is that you get a catalyst that will give you at least 45 minute geltime.
     
  2. groper
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    groper Senior Member

    Indeed, the polyester taffeta is "polyester liner" - but be careful its just plain and not added gloss with silicon contaminants which will cause you headaches for secondary bonding...

    I use 1/2" irrigation tubing for all the resin and vac lines. Try weeping irrigation hose for the vacuum line - you could even wrap it with tyvek to make your own MTI hose!
     
  3. Steve W
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    Steve W Senior Member

    Thanks guys, how can you tell if the taffeta has silicone added? I bought a few yards from the fabric store yesterday and, apart from the color I cant tell the difference from the peel ply, the sheen looks about the same so I laid out a scrap of each out and poured water on them thinking that it would bead up more if there were silicone present and to my surprise it just went straight through the taffeta without any beading but beaded a little on the peel ply before wetting through so I think the taffeta looks good. Further testing to come before I use it on a project. I find the irrigation hose a pain to work with because i just cant get it to lay straight but I can live with that with its very low cost.
    Andrew, i will look into a different catalyst to give a longer gel time, they really don't recommend catalyzing at less than 1.5%. This is why i was thinking of using separate buckets to feed each line rather than adding fresh to already partially gelled in the pot, a little more complex but essentially lengthening the gell time and preventing having excess mass creating exotherm in the pot. Have you guys found an economical bag material? The stuff i have at present is a polyester film, looks like mylar at 120" wide and is costing me $4.50/lineal yard, i would like to find something cheaper but it needs to work with esters and im not sure regular poly films would do so, doing a seach for mylar online yields nothing over 48" wide and indeed a lot of the film sold as bag film is not wide enough for any sizable project so people must be joining to make bigger bags, how do they do this?

    Steve.
     
  4. groper
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    groper Senior Member

    Chances are its ok... the stuff to watch out for looks very glossy and feels a bit more slippery to the touch. Thats about all i can offer...

    The bag film we use wont work with styrene resins... The styrene starts to dissolve the PE...

    You can add a retarder/inhibitor to VE resin to slow down the gel time - i forget the chemical name as its been years since ive used it. Your composites supplier should be able to get it for you and you only need a few drops added per quart and it will extend the gel out to a couple of hours if need be, 1 or 2 drops will get you to 45mins or thereabouts... dont know if its possible with PE resin tho, never tried it...

    They join the film with tacky tape for large jobs... for ester resins, the proper vac film is a laminated nylon IIRC... i did find a manufacturer here in australia that made most of the plastic films everyone sells - they said they could make me any film i wanted including a laminated nylon but for small runs its simply cheaper to buy it from the composites supplier... sorry cant help much more than that...
     
  5. AndrewK
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    AndrewK Senior Member

    I guess the ultimate test for the peel ply is to do secondary bond peel tests., samples with peel ply and others with sanding only. This is what I did, I know it is subjective only but still a good guide. Thinking about it now a water bead test on a laminate sample after the peel ply has been striped is also a good indicator if there are any contaminants left behind.
    A friend workd in the textile industry his recommendation is to buy white fabric as the manufacturer takes extra care when making this as compared to solid colours, sometimes the white material even gets washed to make sure there is no visible staining.
    Dont infuse with PE/VE resin, have helped a friend with VE, he was not using a retarder but two chemicals that gave a 60 min gel time. Do a google serch or ask your supplier.
    Also search the forum, there must have been previous discussion on this.
     
  6. Steve W
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    Steve W Senior Member

    I think I will do some more test panels on the glass table with 4 layers of biax but no core to test the taffeta and also to get a better handle on my glass/resin ratio or maybe with core bit a layer of perforated release film between it and the glass. The peel ply I bought is apparently treated but I don't know with what, I just did a test for water beading on the sample I had done and it did not bead up on the peel ply side but of course did on the tool side, either from the release wax or just being shiny. I will try bonding to it with and without sanding. As I said, the water wet right through the taffeta better than the peel ply. Good tip on the white taffeta instead of colored. The bag material I have looks like polyester/mylar and has no stretch so needs plenty of pleats, I took a piece of it over to a friends shop who builds weather balloons out of mylar, he has from .25 mil up to 2 mil (.002") my bag film looks like 1.5 mil. The problem im finding in looking for a substitute is finding wider material,what I have is 10ft wide and I havnt found anything else over 5 so ill probably stick with what ive got for now,its pretty reasonable any way at 15 cents/ft2. The peel ply was the bad one at 52 cents/ft2. I made a call to my supplier and they had the catalyst to extend the gell time, so I ordered some, its called MCP slow catalyst. Now if only this cold weather would break, its hard to get the temperature where I need it to be when its -16F outside.

    Steve.
     
  7. Steve W
    Joined: Jul 2004
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    Steve W Senior Member

    Heres my first actual part. I will have some questions about this and hopefully more photos but for now the part is still on the table.
     

    Attached Files:

  8. groper
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    groper Senior Member

    There would have been a bit of a dry spot far left, can see your flow markings... the distance to that corner was further than the edges everywhere else. You need to keep the distances more even from feed to panel edge... also I would have stopped the flow media 2inches from the top of the chamfered edge. This helps even out the front by letting the further distances catch up and also allows the bottom to catch up to the top. If you don't get rid of the lag, you can get dry edges On the bottom as the vacuum is cut off once it goes over the edge and saturates the peel ply...
     
  9. Steve W
    Joined: Jul 2004
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    Steve W Senior Member

    Thanks, I have a second mirror image part to make and I will hold the mesh back as suggested, actually the top was fully wet out way faster than I would like to see, it wet fairly evenly but only took 5 minutes, I estimated the resin at 2 gallons based on the test panel I had done and that's exactly what it took, I backed off the vacuum to 24 hg as it started drawing resin from the top which is what you are seeing I think, I hope the bottom side wet all the way, I will find out tomorrow. I really don't like how fast the top moves, I mixed 1 gallon and had another measured out plus another separate quart ready to add catalyst, the first gallon was gone in less than a minute and I had to shut it off so it wouldn't suck air while i mixed the next batch, I meant to throttle back the feed but forgot.

    Steve.
     
  10. groper
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    groper Senior Member

    Stop the resin runner shorter in that little sharp corner, pictured on the right, it would have spilled over the edge almost immediately and started running around the edge of the panel?

    Take another runner, or a strip of extra flow media out towards the corner that was last to wetout, promote some flow that direction so it fills more evenly...

    For small panels like this, you could reduce the feed line diameter considerably...

    And you will get frustrated with grinding off the resin line print using using a large spiral hose on the job like that - think about alternatives now, smaller diamter or pull them up into a pleat so theyre above the panel, or a different runner altogether - like something that lays flat...

    One more thing - when infusing flat panels of odd shape, i found it better to simply infuse a rectangular panel and cut it down to exact size afterwards with a circular saw and a triple chip plastic cutting wheel, or a steel cold cutting wheel (not the abrasive type). It cuts just like a piece of plywood using the same tool... Yes there is a bit of waste, but i found these often can be used in other parts of the boat to make stringers or brakets, shelves, step treads, the list is endless... Setting up a large panel and cutting it up is much quicker - i can do a 20ftX8ft panel working solo in 4 hours, bare table to clamping off and waiting for cure. Next day, you cut it up into multiple parts - which needs to be done regardless as you otherwise need to trim the flash.
     
  11. Steve W
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    Steve W Senior Member

    Well, I popped the part off the table today and was relieved to find that it did completely wet through, it is a little drier than I would like to see but even, nothing I need to do anything about. You were right about the ime better suited to aprint of the feed lines. Im setting up to do another and then will proceed with the swim platform. These first parts would better suited to wet lam really but I need the infusion experience.

    Steve.
     
  12. Steve W
    Joined: Jul 2004
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    Steve W Senior Member

    This is the second part. I took your advice and held the flow media back, shortened the resin tubes, and added a second layer of flow media to the extremities. This all worked very well as you can see by the remaining resin in the pot. It took twelve or thirteen minutes to wet out from the time the resin was introduced. Once wet out the vacuum was turned off until the resin kicked. Total time about an hour. Im pretty confident that this part is a marked improvement over the last.
     

    Attached Files:

  13. Tungsten
    Joined: Nov 2011
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    Tungsten Senior Member

    How do you find the Amprobe leak detector?I'm having a hard time finding a brand that is known and will ship to Canada.Amprobe is one.
     
  14. Steve W
    Joined: Jul 2004
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    Location: Duluth, Minnesota

    Steve W Senior Member

    To be honest so far I am finding the thing useless, were having a lot better luck just using a piece of hose to the ear to listen for leaks, but to be fair I havemisplaced the owners manual so havnt figured out how to use it properly. I just bought a mechanics stethoscope today at Harbor Freight for $2.99 and am going to give it a try. Of the 3 parts weve done so far we have been able to pull full vacuum first try and very slow leak down. On the part we just did we shut the pump down as soon as infusion was complete and it had only dropped to 24hg by the time exotherm was complete and it was cooling down, this is one of the reasons I like about ve.

    Steve.
     

  15. Tungsten
    Joined: Nov 2011
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    Tungsten Senior Member

    Ya the hose in the ear works well,much better then the stethoscope you'll find.Its the small leaks that you can't here that will cause a bunch of trouble.
    Thanks for the tip on the slow catalyst,I'll ask about it.I was told that I could reduce the promoter a little to 3ml per gallon and this would give me a little longer time??.
    Ya I agree the quick set time is nice with Ve an hour after you close the line you can go to bed with out worry.
     
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