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Thread: fumed silica VS. phenolic microballoons

  1. #1
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    Default fumed silica VS. phenolic microballoons

    Why use phenolic micro-balloons instead of fumed silica ?? Fumed silica seems to be better for anything than phenolic micro-balloons. The only sometimes desirable characteristic of micro-balloons is color. I can see where epoxy mixed with micro-balloons has been applied.

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    Default Re: fumed silica VS. phenolic microballoons

    Micro balloons are much easier to sand than fumed silica, so are better for making fairing compound or as a topcoat over silica filled fillets and other non-structurel uses.

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    Default Re: fumed silica VS. phenolic microballoons

    Quote Originally Posted by kc8pql View Post
    Micro balloons are much easier to sand than fumed silica, so are better for making fairing compound or as a topcoat over silica filled fillets and other non-structurel uses.
    Gosh, one of the most unassailably correct answers ever given in here, and on the first bounce, too. I can say categorically that if anybody chimes in to say otherwise, they are wrong.
    Last edited by Bob Cleek; 07-23-2014 at 08:40 PM.

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    Default Re: fumed silica VS. phenolic microballoons

    Even easier to sand than the red stuff (west407) ,phenolic baloons , is west 410...microlite.
    All these fillers have a different purpose. I do not like fumed silica simply because it blows around and is a PITA to mix.

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    Default Re: fumed silica VS. phenolic microballoons

    Microlite is probably a bit easier to paint too. Micro balloons, being hollow spheres, leave tiny little holes when you sand. That can make a rough finish when you paint unless you
    use a seal coat of resin, or high build primer.

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    Default fumed silica VS. phenolic microballoons

    Quote Originally Posted by kc8pql View Post
    Microlite is probably a bit easier to paint too. Micro balloons, being hollow spheres, leave tiny little holes when you sand. That can make a rough finish when you paint unless you
    use a seal coat of resin, or high build primer.

    Microballoons run c. 50 microns or so in diameter. P120 sandpaper (FEPA), more than sufficient for a good paint job, uses 125 micron grit. It leaves scratches more than twice as deep. Once you slap a coat of paint on it, you don't see the scratches.

    Ditto for microballons.

    The difference between microballoons, colloidal silica, wood dust, cotton fibers and other types of fillers are the uses for which they were engineered. Microballoons, and similar fillers were engineered for making easily sanded, non-structural puttys; other stuff is designed for varying degrees of structural uses (trading off ease of sanding for strength).
    Last edited by Nicholas Carey; 07-23-2014 at 11:22 PM.
    You would not enjoy Nietzsche, sir. He is fundamentally unsound. P.G. Wodehouse (Carry On, Jeeves)

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    Default Re: fumed silica VS. phenolic microballoons

    Another thing to be aware of with cabosil or other types of fumed silica - you really don't want to breathe it. And it does poof up as you stir, so you must be CAREFUL not to breathe it. Silicosis is no fun. Dying of mesothelioma is a stone drag. I watched my f-i-l do it.

    And, Bluegill, if you're going to be using epoxy - please DO read up on it. Go to the West System site, and download some of their how-to info. Even the book is a free download these days!
    David G
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    Default Re: fumed silica VS. phenolic microballoons

    Quote Originally Posted by Nicholas Carey View Post
    Once you slap a coat of paint on it, you don't see the scratches.
    Depends on the required quality of the finish. 12 years of experience in my younger days building molds, patterns and prototypes for Owens Corning Fiberglas R&D tells me otherwise.
    The paint job on a prototype Corvette hood comes to mind...

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    Default Re: fumed silica VS. phenolic microballoons

    Wow.

    I am surprised that no replies mention the fundamental difference in purpose of these two products. Bob, what were you thinking? It is not a matter of one vs the other. Fumed silica is a thixotropic agent and not a filler. Micro balloons, Q cells, sanding dust and other similar materials are primarily filler or bulking agents and are not very useful for thickening the epoxy mix. Fairing mixes usually contain both fumed silica and a filler like balloons for easier sanding. Just enough fumed silica to prevent sagging and whatever amount and kind of filler is desired for the particular job.
    Tom L

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    Default Re: fumed silica VS. phenolic microballoons

    Thixotropy is not a household word. You are not the average goop mixer. Good information as always, but you do speak a foreign language. We should add that the mix of hollow spheres and resin is called a syntactic foam. The theoretical maximum by volume is 65% microspheres, but that would be too stiff to stir.

    More on Microlite 410: http://forum.woodenboat.com/showthre...410-Microlight Post #7

    The Microlite 410 MSDS indicates a mix of acrylic microballons and glass microballoons with some fumed silica to make a smoother more easily handled concoction. At $75 per pound, I might think twice before buying the mix instead of mixing my own from $6 and $10 per pound ingredients. I have never used acrylic microballons, which are described by D&S as "Hollow spheres made of acrylic. Acrylic microballons are lighter in weight than glass microballoons but cheaper than phenolic microballoons. The only draw back to using acrylic micro-balloons is that they are not as resistant to certain solvents" It seems from the older thread that there are more drawbacks than D&S mentioned.

    Phenolic, glass, or acrylic Microballoons produce a low density, more easily sanded filler. The strength of a highly filled mix of epoxy and micro-balloons is roughly half that of neat resin, which is not insignificant. For a stronger, but denser hollow sphere, there are cenospheres. Fumed silica produces the largest increase in viscosity for the smallest amount of filler, and is difficult to sand.Thickening with fumed silica alone uses a lot of expensive epoxy for the volume as compared to more reasonably priced bulk fillers. As a thixotropic agent, a small amount of fumed silica helps to prevent sagging and makes the mix easier to work with.

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    Default Re: fumed silica VS. phenolic microballoons

    A pound of microlite(west410) , even for me , would be a 5 year supply . key word ..... lite..
    dave , how can you comment on something that you have never used?
    i try to avoid that .I try to help folks with stuff I have actually done , NOT crap, whoops... sorry ,, stuff, that i read in a book or read on the internet.
    have you bought , or used , the acrylic thingys from douglas and sturgess?
    have you used "cenospheres"?
    bruce

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    Default Re: fumed silica VS. phenolic microballoons

    Quote Originally Posted by MN Dave View Post
    Thixotropy is not a household word. You are not the average goop mixer. Good information as always, but you do speak a foreign language. We should add that the mix of hollow spheres and resin is called a syntactic foam. The theoretical maximum by volume is 65% microspheres, but that would be too stiff to stir.

    More on Microlite 410: http://forum.woodenboat.com/showthre...410-Microlight Post #7


    The Microlite 410 MSDS indicates a mix of acrylic microballons and glass microballoons with some fumed silica to make a smoother more easily handled concoction. At $75 per pound, I might think twice before buying the mix instead of mixing my own from $6 and $10 per pound ingredients. I have never used acrylic microballons, which are described by D&S as "Hollow spheres made of acrylic. Acrylic microballons are lighter in weight than glass microballoons but cheaper than phenolic microballoons. The only draw back to using acrylic micro-balloons is that they are not as resistant to certain solvents" It seems from the older thread that there are more drawbacks than D&S mentioned.

    Phenolic, glass, or acrylic Microballoons produce a low density, more easily sanded filler. The strength of a highly filled mix of epoxy and micro-balloons is roughly half that of neat resin, which is not insignificant. For a stronger, but denser hollow sphere, there are cenospheres. Fumed silica produces the largest increase in viscosity for the smallest amount of filler, and is difficult to sand.Thickening with fumed silica alone uses a lot of expensive epoxy for the volume as compared to more reasonably priced bulk fillers. As a thixotropic agent, a small amount of fumed silica helps to prevent sagging and makes the mix easier to work with.

    All in good humor I hope, Dave. Thixotropic and Syntatic are certainly not a household words, but boatbuilding is seldom done in the house. A user of epoxies would be advised to read some of he really informative literature from several epoxy suppliers before making any serious boat building efforts with it. Yeah, I know, it goes against the grain of the male to actually read instructions before embarrassing himself assembling the kids Christmas toys.

    Another important point is that thixotropy, thicken and viscous are very different in meaning and the difference needs to be absorbed before the epoxy gremlin bites you. Honey is viscous while mayonaise is thixotropic. Big difference. Removing some water from honey makes it more viscous, not thixotropic.
    Tom L

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    Default Re: fumed silica VS. phenolic microballoons

    Quote Originally Posted by Tom Lathrop View Post
    All in good humor I hope, Dave. Thixotropic and Syntatic are certainly not a household words, but boatbuilding is seldom done in the house. A user of epoxies would be advised to read some of he really informative literature from several epoxy suppliers before making any serious boat building efforts with it. Yeah, I know, it goes against the grain of the male to actually read instructions before embarrassing himself assembling the kids Christmas toys.

    Another important point is that thixotropy, thicken and viscous are very different in meaning and the difference needs to be absorbed before the epoxy gremlin bites you. Honey is viscous while mayonaise is thixotropic. Big difference. Removing some water from honey makes it more viscous, not thixotropic.
    Let me reinforce that point. In any given thread about epoxy, I see some good advice, some bad advice, some obscure advice, and some that's a mixture of all of that. 90% of the questions asked here could be avoided if people would simply read up a bit from the readily available resources. One of the best is West System. They have the big book, and lots of pamphlets. They're available in hard copy for a fee, or as FREE downloads.
    David G
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    https://www.facebook.com/HarborWoodworks/

    "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

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    Default Re: fumed silica VS. phenolic microballoons

    Quote Originally Posted by Tom Lathrop View Post
    Wow.
    I am surprised that no replies mention the fundamental difference in purpose of these two products.

    All in good humor I hope, Dave.
    Good humor? I try for good, but may not always succeed. Yes, my comment was a tongue in cheek way of suggesting that I was surprised that you were surprised. You post good information based on more studied and measured experience than most of us have the facilities to produce. You can increase both viscosity and thixotropy with Cab-o-sil. It also helps keep the microspheres from floating to the surface before the epoxy sets up.

    Quote Originally Posted by wizbang 13 View Post
    A pound of microlite(west410) , even for me , would be a 5 year supply . key word ..... lite..
    dave , how can you comment on something that you have never used?
    i try to avoid that .I try to help folks with stuff I have actually done , NOT crap, whoops... sorry ,, stuff, that i read in a book or read on the internet.
    have you bought , or used , the acrylic thingys from douglas and sturgess?
    have you used "cenospheres"?
    bruce
    Your advice is generally sound and based on years of experience, when you are being serious anyway. Don't carp about my crap until you think it through.

    I have used hollow glass and phenolic spheres. I commented on the acrylic because anyone who uses Microlite 410 is using acrylic whether they know it or not, and I gave a link to some commentary from people who have used it and know more about it than I do. I do comment on things that I have never used, and when I do, I say so. Based on what I have read, I don't see much to recommend acrylic since the only advantage is a small cost savings on a product that you don't need much of. As for Microlite 410, you pay a premium for the convenience of a reasonably well thought out mix and ready availability, and in a pinch, I will pay the freight. As for the link to D&S, do you know any other source of the material or where to find any information on it?

    Cenospheres? You got me there, I have not used them and did not say so, but I can make a reasonable estimate of the properties that will result from using them. Why mention them? To complete the list of available light weight fillers consisting of hollow spheres. Someone might get interested enough to tinker with them and come up with something worthwhile. What's wrong with a potentially lighter and fairly abrasion resistant mix?

    I have had to recommend and try things that I have never used many times over the years when designers have painted themselves into some pretty tough corners. Sometimes you have to read and make informed decisions based on the available information. Sometimes no one has ever used the materials before, at least not in production. Not all of the 'boats' that I have made or worked on were wood, manned, strictly aquatic, or always stayed on the surface of the water. Some were fiberglass, aluminum, steel, titanium or all of the above.
    Last edited by MN Dave; 07-29-2014 at 12:43 AM. Reason: timed out, restored auto saved content, lost information

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    Default Re: fumed silica VS. phenolic microballoons

    no one mentioned the specific gravity of the microspheres. I sell 0.28 and 0.6 (g/cc) or so - most places sell the heavier/denser 0.7 (grams/cc)

    lots of folks bend the different fillers

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    Default Re: fumed silica VS. phenolic microballoons

    Quote Originally Posted by David G View Post
    Let me reinforce that point. In any given thread about epoxy, I see some good advice, some bad advice, some obscure advice, and some that's a mixture of all of that. 90% of the questions asked here could be avoided if people would simply read up a bit from the readily available resources. One of the best is West System. They have the big book, and lots of pamphlets. They're available in hard copy for a fee, or as FREE downloads.
    You got it brother...the next time someone comes on here and asks, "How do I varnish?", I will have to be restrained. How lazy can you get?

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