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aldebaran
11-12-2010, 02:59 PM
Has anyone tried using standard refined wheat flour or corn flour as an epoxy thickener. Im out of good quality wood flour and I have a lot of wheat flour in the house. I know that wheat flour will rot if left in humid conditions but so do most wood flours and besides, itll be totally soaked in epoxy

Pros and contras or just opinions?

knottyBuoyz
11-12-2010, 03:02 PM
I'd do a small test, see how it goes. The pecan flour I have is as fine as white sifted flour.

Peacefuljourney
11-12-2010, 03:51 PM
Has anyone tried using standard refined wheat flour or corn flour as an epoxy thickener. Im out of good quality wood flour and I have a lot of wheat flour in the house. I know that wheat flour will rot if left in humid conditions but so do most wood flours and besides, itll be totally soaked in epoxy

Pros and contras or just opinions?

Yeah I do and still do it. I've fix fiberglass boat for long time in boat yard (I know it's a shame, but it paid more then wood boat), and this is what we use regular white flour for fairing or in other area. At that time I learned this tricks I made research on it and it's considered as silica power, having structural slighly lower then it in heavy spread as silica give a bit more structure to it.

Peacefuljourney
11-12-2010, 03:56 PM
Ohhh and don't tell the customer, we used to put the flour in a old silica barrel or a strange bag, so it look really good stuff in front of the owner ;)

JimConlin
11-12-2010, 04:00 PM
Sigh!
What the hell! It's only a boat and he customer doesn't know any better.


I'm tired of this nonsense.

Peacefuljourney
11-12-2010, 04:24 PM
Sigh!
What the hell! It's only a boat and he customer doesn't know any better.


I'm tired of this nonsense.

A well you know how it is... Fancy customer, specially on fiberglass boat, love fancy words and technology stuff. Regular flour doesn't sound enough good for them, maybe something like : niveus farina oh! That sound way better (Same thing but said in latin)...

Try after to explain to them that a carvel wood boat have only cotton to keep them tight, they will think we are back at stone edge time!

Peacefuljourney
11-12-2010, 04:28 PM
niveus farina 250g filtered, it's just as good.

Sound good for what it is no? :)

davebrown
11-12-2010, 05:10 PM
HMMMM. I am reading this with interest, because I go to the trouble of running a belt sander on suitable wood and then filling a tub for use as filler. I put the sander in a vice and clamp the wood lightly and go do other things. It's still trouble though. Are you sure you're not confusing this with wood flour? No offense intended.

Peacefuljourney
11-12-2010, 05:16 PM
HMMMM. I am reading this with interest, because I go to the trouble of running a belt sander on suitable wood and then filling a tub for use as filler. I put the sander in a vice and clamp the wood lightly and go do other things. It's still trouble though. Are you sure you're not confusing this with wood flour? No offense intended.

Nop I am not confusing, type "Wheat flour epoxy thickner" On google and you will be surprise ;)

It act pretty much the same, and flour being dry soak up all the epoxy and work with each other to give a good result. Flour it's not chemical either, so no bad reaction can happen there. Like using white oak wood flour, or other wood hard on epoxy would make more damage that I am sure!

It also give a nice smooth finish, better then wood flour. Perfect for fairing or rounding corner.

davebrown
11-12-2010, 05:23 PM
Are we talking structural or fairing? It sure would save me a lot of trouble.

Peacefuljourney
11-12-2010, 05:32 PM
Are we talking structural or fairing? It sure would save me a lot of trouble.

I use it mostly for fairing, structural well it's rare I got a so big join in a structural piece that I need to put so much filler to fill a big gap.

If there is a big gap, and it's structural better doing it again!

But I read somewhere in a study that it's pretty much like silica in term of structure. Just slightly lower on paper, but not enough to say it's terrible.

BillyBudd
11-12-2010, 05:44 PM
Wood to wood joinery -- especially structural joinery? Wood flour in the epoxy. Somewhat similar characteristics and color, works similarly, no? For wheat flour might I humbly suggest the following spectacular options: pasta, bread, pancakes, ravioli...skip the epoxy.

Peacefuljourney
11-12-2010, 06:30 PM
I think the question is more about what are you doing with this?!

Like Billy said, I wouldn't use it if it will be visible in between some wood, for repairing fiberglass boat, stitch & glue construction or something gonna be paint over, I do not see any problem there.

There is around 30 differents powder tested & certified for thickning epoxy all working 100% with wood, the point "Wood dust over wood work better" doesn't make sense...

Peacefuljourney
11-12-2010, 06:34 PM
BTW, chalk is suggested by manifacturer to use as structural filler for Resorcinol & Epoxy.

Black-Jack
11-12-2010, 07:43 PM
Powdered limestone is cheaper than flour - get it at any big box or garden center- and it wont draw bugs like weevil worms or pantry moths.:):)

Just dont tell the customer.

Fitz
11-12-2010, 08:52 PM
and baby powder, - -erh ah, "talc" is sandable.

pipefitter
11-12-2010, 09:02 PM
Yes, you can ( I have ) use it for fairing but I have never used it for a structural thickener. I would only use it under a good sealer coat of epoxy, or something like killz pigmented shellac because if you just paint over it sanded, you can get powdery mildew through the paint. It seems that just enough of the flour particles are exposed thru sanding to give mildew something to live on. It is a bugger to sand though if you are planning on hand sanding so I would make any coats as tight as possible and feather all edges to zero. I would be more inclined to use it as a fine spot putty rather than fairing that requires any depth to it. The boat I used it on is going on 6 yrs old and no signs of problems with it.

Edited to add: Here is a picture that shows a spot I used it on and how I used it. Also shows the zero feathered edge aft I referred to above.

http://home.earthlink.net/~tigmaster41/sitebuildercontent/sitebuilderpictures/104-0578b_img.jpg

Peacefuljourney
11-12-2010, 10:02 PM
Yes, you can ( I have ) use it for fairing but I have never used it for a structural thickener. I would only use it under a good sealer coat of epoxy, or something like killz pigmented shellac because if you just paint over it sanded, you can get powdery mildew through the paint. It seems that just enough of the flour particles are exposed thru sanding to give mildew something to live on. It is a bugger to sand though if you are planning on hand sanding so I would make any coats as tight as possible and feather all edges to zero. I would be more inclined to use it as a fine spot putty rather than fairing that requires any depth to it. The boat I used it on is going on 6 yrs old and no signs of problems with it.

Edited to add: Here is a picture that shows a spot I used it on and how I used it. Also shows the zero feathered edge aft I referred to above.

http://home.earthlink.net/~tigmaster41/sitebuildercontent/sitebuilderpictures/104-0578b_img.jpg

Yep, I have found mildrew was not much of a problem with time as the flour was soaking well the epoxy. But most of my work done on boats were heavy painted after so... I found it perfect for doing round corner before laying fiberglass cloth over so the fiberglass can follow a smoother curve. This take lot's of thickener in a area where fiberglass will already put structure over it.

Jimbo2004
11-12-2010, 11:14 PM
and baby powder, - -erh ah, "talc" is sandable.

And absorbs water as well as flour

aldebaran
11-13-2010, 03:51 AM
And absorbs water as well as flour

Wood flour also absorbs water and will rot to.

Thanks for the replys everyone. I have done some tests and I liked the result. Thats why I asked here. Maybe because I found it to be to simple.

I will go ahead and use it. I will use wheat flour or cornstarch for fairing small spots and simply making the glue thicker and I will mix wheat flour with some sawdust for structural work.

The boat is not for a costumer but for myself.

Fitz
11-13-2010, 08:37 AM
What is Talc?
Talc is the world's softest mineral. Although all talc ores are soft, platy, water repellent and chemically inert, no two talcs are quite the same. Talc is a vital part of everyday life. The magazines we read, the polymers in our cars and houses, the paints we use and the tiles we walk on are just some of the products that talc enhances. http://www.ima-na.org/IMA-NA/files/ccLibraryFiles/Filename/000000000079/stockxpertcom_id120285_jpg_789bf6ec3fe18cd257dda3b ba9b0ea4d-92x123.jpgTalc is a hydrated magnesium sheet silicate with the chemical formula Mg3Si4O10(OH)2. The elementary sheet is composed of a layer of magnesium-oxygen/hydroxyl octahedra, sandwiched between two layers of siliconoxygen tetrahedra. The main or basal surfaces of this elementary sheet do not contain hydroxyl groups or active ions, which explains talc's hydrophobicity and inertness.
Talc is practically insoluble in water and in weak acids and alkalis. It is neither explosive nor flammable. Although it has very little chemical reactivity, talc does have a marked affinity for certain organic chemicals, i.e. it is organophilic. Above 900C, talc progressively loses its hydroxyl groups and above 1050C, it re-crystallizes into different forms of enstatite (anhydrous magnesium silicate). Talc's melting point is at 1500C.

http://www.ima-na.org/talc

SBrookman
11-13-2010, 11:55 AM
I bought 25# of Talc (Magnesium Silicate) from CQConcepts (http://www.cqconcepts.com/chem_magnesiumsilicate.php)a couple of years ago for less than $25 and use it for all non-structural mixing. I think I have enough to build any and all boats on my dream list.