wheat flour epoxy additive

Discussion in 'Boatbuilding' started by Collin, Nov 2, 2012.

  1. goodwilltoall
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    goodwilltoall Senior Member

    Did read about WA a few years ago but found very little laymans info now, even at WEST.

    Peace.
     
  2. PAR
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    PAR Yacht Designer/Builder

    This may be the problem, as the preformance of major brands, including moisture vapor transmission, have been well covered. A lot of West's testing is published separate from their books and user's guides. Many are available in PDF format though.

    Simply put, once epoxy is properly applied, the key to water proofing is film thickness over the sealed surface. Now, you will get lots of flack from those that haven't conducted "reasonable" testing, such as Dave in some cases, but real testing as repeatedly shown the sealer coat(s) fill the cellular tubules at the surface and the sufficiently thick over coats prevent ingress. A small percentage (3% or less) of the cut tubules will accept some moisture, but these remains at a very low level, keeping wood from expanding with increased content and as you've pointed out low enough to prevent beasties from making a home. Some will have you believe it's all about penetration (like Dave), but in reality and confirmed by testing (many) it's not the level of goo penetration, but the quality of the coating, regardless of penetration. This is where nearly every other product fails in comparison to epoxy. Paints (high end) generally fall into the high 20% low 30% range, some specialty paints, can lower this a few percent. Polyester resin is actually lower then some of the better paints and vinylester resin is in the 10% range. Then of course are the solids contents, which again is a tell on waterproofing products. Most marine epoxies are 100% and paints aren't even close.

    Simply put, once a wooden surface is sealed and sufficiently over coated, it's literally waterproof. It doesn't continue to absorb moisture, because there's no place for it to live in the cellular structure of the wood. This wood doesn't need to breath, doesn't need to dry out nor soak up. It's dimensionally stable and the moisture content is frozen at the point it was when the coating cured, so if you started with dry stock, it will remain so, minus about 2 - 3 percent, if continuously immersed. There's no debate on this, it's long been proven in tests and log term trials.
     
  3. goodwilltoall
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    goodwilltoall Senior Member

    Greetings,

    Would like to see those tables showing water resistence. Read over "Gougeon Bros. Boat Construction", they make subtle remarks concerning water ingress, people use it as the best authority for technique/methods and use thier specifications for low moisture wood content as the accepted best practice.

    Quote: "When using wood in composite with West System epoxy, it is important to use only wood which has a moisture content of 12% or less, 8-12% percent is ideal. Boats can be built with wood with moisture levels up to 18% but in long term equilibrium, they may lose moisture content, which could affect structural intergrity because of internal stressing from shrinkage"

    With that statement they admit changing moisture levels are possible and in fact happen.

    Next Paragraph: "We keep our shop at 65 degree F., with relative humidity of 50%, moisture equilibrium is 8%".

    8% moisture equalibrium is desert, Eastern America is 13-18% and more in some prime coastal boating areas. Had readings of 13-15% for 3/4" stickered softwood that was drying in the loft for 8 months, and this in an unusually dry year. BTW, the $13.00 Harborfreight moisture meter worked well.

    AS an Aside: "upto 18% allowable" is that when rot is possible? Most big box lumberyards usually had levels under that excluding the treated woods.

    Rather than building for the service environment, there method remains in a closed system-built for the needs of thier shop. Which as they admit will seek moisture equalization. When exposed to more realistic exterior usage it will eventually subject materials to moisture ingress and accompanying stresses.


    They recognized excess moisture loss will cause stress but failed to look at the other end of equation-tight fitted wood/epoxy resulting in expansive forces when adjusting to moist environments.

    Here's a qoute from Ed Petrie in "Epoxy Adhesive Formulations":

    "Certain substrates, notably wood but also other materials such as laminates and certain plastics, will change dimensions significantly when exposed to variations in ambient relative humidity or moisture. Wood is an anisotropic material, so dimensional change will be greater in one direction than in another. Such change with relative humidty can result in large internal stress on the joint and even warpage of assembly. The adhesive must be selected to withstand these dimensional changes.

    Maximum bond performance and minimal internal stresses are sometimes achieved if the substrate has a moisture content during bonding that is close to the average moisture content anticipated during service-provided, of course, that the moisture retained in the substrate does not adversely affect the initial bond strength."

    Without seeing WESTS facts, these statements are in accord with what Dave Carnell observed; with time, a few samples pieces, and a scale this experiment could be performed easily. Never heard of Dave advocating penetration and would say he was contrary to that opinion considering his conclusion that epoxy is not an absolute sealer.

    If you say 2-3% penetration is possible and the norm, whats to stop further ingress, and over what time frame did that much water enter? Its necessary to see further than 30 days, at least 2 years and more if available.

    Petrie mentioned a process called "hydrolysis", its a complete breakdown of the epoxy molecules caused by excessive moisture ingress and temps that are typically tropical. With accelerated conditions this has happened to many epoxies at 2 year service rates, annhydrides are more prone but also happens to amines, both are used in marine epoxies. This wouldnt be possible if epoxy is inert after curing.
     
  4. goodwilltoall
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    goodwilltoall Senior Member

    "Ironite": Here's a possible filler material I hope to experiment with someday.

    Its only manufactured in Cleveland and only use I know is for water resistance. Produced in powder form, the 5gal bucket weighs about 200lbs. When it contacts water the particles expand (rust), filling in gaps allowing water entry. Its very hard when combined with other materials and would have interesting qualities.

    Peace.
     
  5. PAR
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    PAR Yacht Designer/Builder

    Your understanding of the chemistry is flawed Goodwill. If what you suggest is true, lots of balsa and other cored methods would be saturated with water by now. Countless sheathed plywood boats would be twice their weight as a result of continuous moisture gain, from constant immersion. I live in the tropics and have countless builds and repairs under my belt over the years, none yet experiencing anything like what you seem to envision. It would seem that one of us is incorrect and the sewer and water pipe repair outfits, that have been using epoxy to fix leaking pipes for the last few decades, using epoxy, the contractors using epoxy to replace anchor shields in concrete and of course the marine industry, must strive to keep up with your obviously superior knowledge on the subject.
     
  6. goodwilltoall
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    goodwilltoall Senior Member

    Par: Without some stats showing water ingress rates, you have no evidence to the contrary of whats presented.

    Moisture content according to ambient relative humidity is whats referred to, it will not achieve saturation, those boats you built have reached ARH and thats it. The infrastructures project referenced are built for a certain period of service and then eventually begin to diminish in capabilities. Epoxy is used in products you see or use everyday- cars, aircraft, electronics, etc..., it has a certain time frame for service life (usually the warranty) then it might fail after that but usually begins to slowly degrade.

    Those sewer projects are mostly in ground with cool stable temperatures, no UV, no cycling, and epoxy is more resistant to immersion than water vapor. Thats why they test in humidity rooms.

    Civil engineers are thought the 3W's-water will win, without accounting for necessary moisture igress and then allowing it to escape is when saturation can take hold. Talked to a waterproofer friend who does his work the right way. Up here most foundations are in basements and constructed of concrete block, then water proofed from the outside. After several years attention is needed due to water entering inside. He repairs it the right way by excavating from outside and resealing walls. Many less expensive waterproofers do it the other way and add a membrane inside with a channel at base collecting water to storm sewer or sump pump. This keeps it dry inside but the walls now have the right conditions for saturation and disintergration can begin.

    Have to stop for a few minutes.
     
  7. goodwilltoall
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    goodwilltoall Senior Member

    Thats the same way I view epoxy composite construction and reason for only two coats inside to allow moisture egress. Rather than cement wall disintergration, saturation/hydrolisis can occur if the inside coats are thicker allowing less water to escape than is coming in.

    Gougeon book quote : "The primary goal of incorporating wood in a composite is to provide fibers with maximum practical protection against moisture."

    They say this and the product they sell is epoxy but, at the end of the book they have wood data stats. Wood is the most tested material of all time, been doing it for millenia, you can get that information from thousands of spots, but nothing on epoxy data and most especially for what they say is the "primary goal". Why would they omit facts on this crucial information? Not infering to the quality of their products, but definitely critical of the book, they should have added this to at least give credence to thier products.
     
  8. goodwilltoall
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    goodwilltoall Senior Member

    Using Gougeon above quote:

    EPOXY main objective is maximum water resistance. Adhesion comes in a close second but you can use fasteners to accomplish this. Tensile, toughness and flexibility are other factors but within parameters of typical marine epoxy capabilities, the minimum requirements of those are easily achieved and their importance can be reduced in relation to the first objective. WOOD most significant material for the structural strengths in epoxy composite construction, achieves the majority of those requirements by itself without needing assistance from epoxy properties, those only enhance, but are not required. FABRICS mainly used for abrasion resistance and elimating fir type checking, typically without regard to structural needs. FILLERS property enhancers.

    The system works as a whole, however it is important to recognize how the individual components perform thier principle tasks, secondary contributions are made but, the primary attributes are why the composite system was designed that way in the first place.

    Gotta go, peace.
     
  9. PAR
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    PAR Yacht Designer/Builder

    Your right and we're all screwing up; have been for decades. Good luck with that . . .
     
  10. rwatson
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    rwatson Senior Member

    The leading edge of composite under adverse ( hi temp) conditions. might be a good start. From what I understand of the graphs and notes, over the 12 days in hi-temp ovens, the epoxy absorbed .06% ( by weight) of water, and had these effects :-

    "In-plane shear strength and modulus both saw a decrease in strength with increasing equilibrium moisture content to a maximum 20% and 10%
    reduction respectively. ILSS saw an increasing-decreasing trend as maximum moisture content increased. Transverse modulus remained unaffected by moisture conditioning.""

    I found this interesting study online,
    http://www.iccm-central.org/Proceed.../INT - AEROSPACE APPLICATIONS/IA2.14 Ryan.pdf

    using epoxy and carbon fibre

    "The objective of this work was to generate material property data for varying levels of saturation in order to quantify the effects of moisture ingress on mechanical properties."


    "5. CONCLUSIONS
    This paper reports the moisture absorption behaviour and performance of unidirectional composite laminate made from 977-2-HTA 12H 34% carbon pre-preg. Moisture uptake in the material agreed well with Fick’s second law. Longitudinal tensile, transverse tensile and in-plane shear properties were studied. Test coupons were prepared and tested to failure as per ISO BS test standards. The results revealed that no effect was measured in test coupons with fibres orientated in the direction of the load, regardless of
    equilibrium moisture content. For tensile strengths of coupons, with fibres orientated perpendicular to the axis of loading, the strength was seen to decrease linearly with increasing equilibrium moisture contents to a maximum of 50% strength reduction as compared to oven dry. In-plane shear strength and modulus both saw a decrease in strength with increasing equilibrium moisture content to a maximum 20% and 10%
    reduction respectively. ILSS saw an increasing-decreasing trend as maximum moisture content increased. Transverse modulus remained unaffected by moisture conditioning."
     
  11. goodwilltoall
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    goodwilltoall Senior Member

    Need to correct mistake above regarding ambient relative humidity (ARH) and average moisture content (AMC). AMC is the water content in the wood and ARH is water content in the air.

    Researched typical AMC for different areas. Here in Ohio it ranged from 12-15%, thought Florida would be the worst on the East coast but it was usually only 1% more than Ohio. Washington state had the highest rates approaching 18% with Spokane the highest.
     
  12. goodwilltoall
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    goodwilltoall Senior Member

    WEST has a good article called "Moisture Exclusion Effectiveness" from EPOXYWORKS Number 25, Summer 2007.

    The test begins with wood samples dried to almost 0% and measures moisture uptake in one room called the Florida Room where temperature is 100degree F. and humidity 100%. After 8 weeks a moisture gain of 8% is achieved. This is quite an extreme test as I dont know anywhere on Earth these type of conditions naturally exist and taking the wood down to 0% will cause a higher rate of increase than say begining with 10%.

    Fig. 2 shows 80degree F. and 90% humidity which at times Ohio experiences and many other areas at East coast. AMC is 20.2 and after 6 weeks moisture exclusion effectiveness has lost 18% which corelates to a 3.64% moisture increase. As you see in the graph, even after 6 weeks it is still on a downward trajectory, it might eventually flatten out and begin to "stabilize" but no reason to give hope and say it is 100% effective at moisture exclusion and preventing wood from eventually achieving it AMC.

    WEST also did a report on one of thier early built trimarans of about 40 years age (maybe called "Addagio"). It praised the qualities of epoxy and it confirms what I've said previously but wonder if they took a wood sample out of an inconspicous spot and tested AMC? Consider also that this is a showpiece boat that they would keep in moderated (indoor storage?) conditions as well as continually correcting any failures quickly to assure the qualities of thier product. Have passed by the Tartan factory and they do this with the original Tartan27 which they showed off at boat shows years ago.

    The interface between water and air would be the most suceptable area for water ingress as that is the dampest spot for air around a boat. Epoxy is very effective below the waterline to the point of saying it is 100% waterpoof if it is a 100% solids epoxy.
     

  13. goodwilltoall
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    goodwilltoall Senior Member

    Watson,

    Unfamiliar with prepeg but, since they have a study concerned with saturation it must be concluded that epoxy picks up moisture content continually and the related loss of strengths whether wood, carbon, or glass must be accounted for. Epoxy wood composite only achieves full stabilization at AMC until then you can only say it is "more stable" according to moisture ingress rates (2 coats is more stable than 1coat, 3 coats more stable than 2 coats, etc...). The real saving factor for epoxy is the exclusion of oxygen which allows rot to develop.

    BTW, two years ago, ironite was selling for $78.00 5gal. pail.
     
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