Wood flour vs cotton flocks

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gonandkarl
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Re: Wood flour vs cotton flocks

Post by gonandkarl » Wed Apr 17, 2019 4:23 am

Hi,
I could not get any wood flour here in Austria either but then I went to shops where they cut big sheets of wood panels and asked for the sawdust which lands at the bottom of these big cutting machines. I could get it for nothing and all I had to do sift the sawdust with a 5 inch diameter fine kitchen sifter which gave me perfect wood flour and any plastic or bigger saw dust pieces were removed. I am sure you have building centres in Poland who give you the sawdust which they would throw away otherwise. I built all my 3 boats with such sawdust except on the first one I did not sift it and the fillers were to rough. Boat number 2 and 3 have only sifted sawdust in the fillers and came out perfect.
Greetings from Karl


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OrangeQuest
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Re: Wood flour vs cotton flocks

Post by OrangeQuest » Wed Apr 17, 2019 5:57 am

I like the fact that wood absorbs water, but it also absorbs the epoxy. The epoxy going into the wood helps it hold together, I would think the same applies to when your are using wood flour or even fine sawdust. Not only is the flour incased by the epoxy but it is through out the inside of the wood fibers so it is as waterproof as the epoxy itself. Can the same be said for the other fillers? "The only fillers you truly need are cabosil or fumed silica and micro balloons." They only have what ever rough surface there is for the epoxy to hold to which is why, I am guessing, it is easier to sand when using these products verses wood. Out of all the products I think the one you would want would be something that the epoxy can soak into and hold onto verses just grabbing the slick surface. I am also guessing that the fiberglass cloth we use also absorbs water or resin and that is what gives it it's strength. And Kevlar does not absorb the resin so is harder to work with because you have to force the resin around it.

These are my guesses and reasoning on one verses others things.
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Re: Wood flour vs cotton flocks

Post by fallguy1000 » Wed Apr 17, 2019 1:45 pm

Cured cabosil is like a rock to sand.

The only things he need is fumed silica is based on his statement about not getting wood flour.

Don't take my words out of context Ken.
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Re: Wood flour vs cotton flocks

Post by TomW1 » Wed Apr 17, 2019 11:51 pm

Fallguy cabosil is fumed silica. See Wikipedia. Do your home work. You have made enough mis-statements here. Wood flour will soak up the epoxy and will be then encapsulated in it. All of the seams will then be covered with fiberglass tape at least in the 6 plans I have that were designed by Jacques. Don't know about your designer. No water can reach them then.

This post is getting out of control and there is no need to keep it going. Bateau sells and have since at least the early 2000's Phenolic micro balloons to thicken there wood flour for making vertical seams. They are then smoothed and covered in fiberglass. As discussed long ago Phenolic balloons may have open spaces on the tops of them, but who cares they will be covered with a layer of epoxy, fiberglass and more epoxy, and depending where they are and the boat up to 8 more layers with a thickness of over an inch or more. By the time you get all of the fiberglass on a Jacques designed boat if you cover it completely, there 'is no wood exposed.

Fallguy, I have spent over an hour composing this trying to make sure that facts are right. Sure, wood flour is hydroscopic but it also soaks up epoxy just nearly as fast. Let's agree on that and quit KICKING A DEAD HORSE

Stachu go ahead and try the wood flour you can get. Then go with the additive you can get from your fiberglass supplier. This is your boat and you asked the question about the wood flour that started this mess.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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Re: Wood flour vs cotton flocks

Post by fallguy1000 » Thu Apr 18, 2019 10:50 am

Stachu wrote:
Mon Apr 15, 2019 6:21 pm
Hello again,
I have hard time getting good wood flour. All the producers I found in Poland sell it only in tonnes :doh: I found only one guy that sells "wood flour" for ordinary people. He says it's fine pinewood dust from a dust collector in his wood pellets factory. Is it good enough?

Alternatively, my epoxy supplier have cotton flocks as an organic filler. Is there any contraindications for using it instead of the wood flour?

Thanks,
-St.
Tom,

What part of I can't get wood flour is not understood?

The wood dust from a pellet factory has an unknown moisture content. It could be low, it could be high, and so I presented a fact.

I have not made misstatements.

Wood takes on moisture.

Cotton takes on moisture and is clumpy and hard to work with.

Fumed silica and cabosil are the same damn thing; no news there Tom. It is not very hygroscopic.

The thread is fine, and I have not made misstatements and I don't need to 'do my homework' on synomyms.

Your point about wood flour being embedded and saturated is well understood. Would you advise someone use wood flour that might be wet?

And why would anyone be concerned with me offering a boat builder and option that he might be able to source?

I even said a lot of bateau guys like wood flour, but the fact is wood flour is not the only solution if it is absent or of uncertain quality.

I filled the front of my canoe with epoxy and sawdust. Solid as a rock, been rained on and in a canoe full of water, never been a problem in almost 20 years. But it is not a fillet material and would leave air in the tape. So, I would not advise it.

The reason you get into jams here, my friend, is you miss the original intent of the original post. And I need your help and appreciate it so I don't want to anger you either, but my message was simple.

If you can't find wood flour; cabosil or fumed silica (yes, same thing) is a good option and no moisture concerns. If he wants to use filter dusts; it should be pretty dry.

By the way; for those of you watching my build, I am using plywood for cockpit gunnels and bench tops and cabin panel base where it is cantilevered. I have no problem with using wood!
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Re: Wood flour vs cotton flocks

Post by Netpackrat » Thu Apr 18, 2019 7:51 pm

My father in law told me that early on in his career as a shipwright, they used to get big bags of "milled fibers" which they would mix with resin and use for various applications. Back in those days there were no particular cautions taken with regard to PPE, etc. Only much later did he learn that those had been milled asbestos fibers. 8O

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Re: Wood flour vs cotton flocks

Post by fallguy1000 » Thu Apr 18, 2019 7:57 pm

Netpackrat wrote:
Thu Apr 18, 2019 7:51 pm
My father in law told me that early on in his career as a shipwright, they used to get big bags of "milled fibers" which they would mix with resin and use for various applications. Back in those days there were no particular cautions taken with regard to PPE, etc. Only much later did he learn that those had been milled asbestos fibers. 8O
Great story. Lots of filler options. I have about four gallons of corecell grindings. I might use them under the plywood for a spacer.

If anyone wants buckets of cotton or can advise what to do with it...probably organic; so can compost..
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