Thread: Epoxy glue powder?

If it pure epoxy powder it will be as hard as nails to sand so be careful where you use it. I use Bote Cote for my build but always use the recommended filler for gluing and filling. They're different for a reason.

The other possible problem is consistency. Sanding dust may have inconsistent particle sizes, as well and sanding grit, etc. In principle yes, you can use it, but it may not be the best option. If in doubt you can always try some for small, non-critical jobs and see how it goes.

Thanks gents.

mike

Pure epoxy dust from a belt or orbital sander is usually pretty coarse, compared to wood flour. This makes for lumpy fillets and doesn't spread out too smoothly either. Epoxy dust also tends to be pretty brittle, so in structural fillets it might crack, without some fibrous materials also in the mix. If looking for cheaper solutions to filler materials, look no further than your other half's pantry. Any good cook will have cooking flour, which is just like the wood flour we use, except instead of being pine or oak or something that once had leaves on it, it'll be made (the same way) from corn, wheat, rice, etc. It's a whole lot cheaper to steal a few cups from the other half's stash, than buy bags of it online. It has the same physical properties as the wooden versions and it'll spread out smooth and even too. While you're stealing stuff from HER kitchen, borrow the flour sifter and use it when you add it to the goo. This tip will save a bunch of heartache when mixing, trust me.

Now, a word of warning. Pilfering supplies and tools from the other half, can rain all sorts of hell on your butt. I've had to repalce the stove, because she caught be drying some oak in it once and if I was to ever get a meal out of it again . . . The same is true of the blender, I was grinding up polyester chips in. In spite of my insistence they were inert and you could eat them with no harm, she was going to shove it in one of my non-speaking orifices, unless I agreed to her terms of surrender. Over the years, I've replaced most of the kitchen applicances as a result of these activities, so if you do plan a colvert black op mission into the kitchen area, wear camo, maybe something that matches the tile on the floor. Insure she's really sleeping or at work and not just waiting to catch your foolish butt in an uncompromising position. Look guys, they're smarter than us, frankly. They know enough to not be boat builders, suggesting they're way smarter than us, so catching a would be flour thief, is just something they live for and you'll pay, I mean really pay. Good luck and erase this thread in your browser, so I don't get dragged into your inability to out think your smarter other half.

Serioulsy I would not use sanding dust from epoxy for a filler.....you have no idea what contaminants could be in there.

there could be

Surplus unreacted epoxy componants ( wax)
anti clogging compounds from the sanding media
grains of abrasive
unknown qualities of things like wood, metal and plastic from the underlying structure or things used to stitch with.

serioulsy the commercial fillers are specifically designed to do what they do.

if you are doing fillets you want strength, if you want a smooth texture or whatever the specfic fillers will do that sooo much better than rubbish that should be tossed in the bin.

cheers

There's nothing about the retail fillers that's' specifically "designed" to be used with epoxy. Silica is a common mineral and found in many things, including foods. The same can be said of phenol spheres, which are commonly used as a bulking agent in lots of things, like women's makeup. Milled fibers are just cut fibers of 'glass, wood flour, is yep, pulverized wood, ground to an very fine powder.

You can spend a small fortune on these things if you like or use reasonable substitutes and a little back woods testing to confirm any suspicions.

I agree in that sander dust (regardless of material) isn't a good choice, if only because it's way to coarse for a fillet. I also agree that some of the "fillet blends" are handy, but they are simply mixtures of stuff you can mix yourself. I use a lot of talc and this is exactly the same stuff they use in the fillet blends, except without the fragrance used in baby powder. In fact, I use enough of it, that I buy talc in bulk and it hasn't any fragrance. I wish I had a machine to grind and cut milled fibers with, as I use this a lot too. I use decomposed granite, cooking flour, printer toner (iron oxide powder), aluminum and bronze powders and several other materials, all with the same or similar physical properties in compression, tension, modulus and hardness. Of course, it helps to have some familiarity with the materials, their combinations and physical properties.

As far as unreacted glycols (amine blush) getting into the mix, well the surface should have been washed, prior to any sanding in the first place. Second, if some broken glycol groups do get sanded, their parts per million after getting mixed with a bunch of other stuff, will be so insignificant, that it wouldn't hurt anything, beside, as soon as the fresh goo hits it, it'll complete it's reaction on a molecular scale. A few stray, weak bond molecules isn't enough to get worried about. Contaminates could be an issue, but again, generally these things will become very small and widely scattered, so not much to worry about. I'd hope most trying this, would attempt to work clean in regard to making their own powders.

I also agree that making fillers requires some practice, to get good batches and most importantly repeatable mixtures. I have a simple chart I use for the various concoctions I make and use a very accurate scale, to measure out quantities. I can make Silver Tip Quick Fair, just like them and at a fraction of the cost (less then 1/10th). If you use much of this stuff, it pisses you off the amount you'll spend on it.

In the end, the only point is you don't have to be married to the retail products, but you do have to justify the added bother, of making and mixing up material combinations. For a one off boat just buy the packaged stuff, but if you do repairs or have a plan to build a few boats, you can save a good bit of money with these home made brews.

Read and comprehend.....I said that "fillers where specifically designed to do what they do"...I did not even remotely infer that they where specific to epoxies.

If I go away from the boating suppliers to my local theatrical, prototyping, moulding and modeling supplier there is a wide range of fillers......and more than are typically used in boating or automotive use.....and they all work with a variety of resins (although some react badly with certain resins)...and they all produce different effects when mixed with various resins.

The filler blends are "specifically designed" to have particular properties when mixed with the resins..and it does make a big difference.

These fillers are not particularly expensive so why some one would use household flour (mostly starch) or crap swept off the floor I have no idea.

I keep half a dozen different fillers on hand..common talc among them......but hell in any given situation.... one or other of the properly formulated commercial filler blends works better than talc...the only think talc is... is cheap.

Talc is not particularly strong, does not sand particularly freely and is heavy in comparison to many other fillers.

Why anyone would compromise a good epoxy (which lets face it IS expensive) with cheap crappy filler is beyond me

Sure you can mix your own filler....but that means you need to know what you are doing AND you have to have sourced the component powders......if you have sourced the component powders...well you should have found better placed to buy and they will no doubt sell you properly formulated filler blends.

If the cost of filler bothers you......shop a bit harder.

cheers

Originally Posted by soundman

. . . Read and comprehend.....I said that "fillers where specifically designed to do what they do"...I did not even remotely infer that they where specific to epoxies . . .

Being one of the engineers that have helped develop these formulations, I can assure you, there is absolutely nothing "designed" about any of the materials used in fillet blends, regardless of the resin system employed. In fact, the resin system used is irrelevant, as they work with any of the common marine resins, used in the industry. Now, some can cause issues with specialty resins, such as the high temperature cure stuff, but very few home builders would even attempt using these resins, if only for their cost, let alone the need for an autoclave to cure it.

Originally Posted by soundman

. . . The filler blends are "specifically designed" to have particular properties when mixed with the resins..and it does make a big difference . . .

Actually, the "specific designed" stuff was just a trial and error thing, until a suitable mix was discovered. No computer models, no physical properties analyses performed, just cups of goo with various thickener ratios placed into test fixtures. Of the common blends, only the fairing formulations have been "refined". In fact, during this testing that we discovered adding various materials to epoxy, lowered the physical properties in unexpected ways. We'd assumed the cured matrix was actually stronger, stiffer, harder, etc., but this wasn't the case. So, we know the physical properties of these mixes, but they weren't designed, just discovered in testing.

Originally Posted by soundman

. . . These fillers are not particularly expensive so why some one would use household flour (mostly starch) or crap swept off the floor I have no idea . . .

If you price up what you get in terms of the actual materials you receive in a premix, particularly if epoxy is included, you'll find an 800% to 1000% markup on the total materials, in the premix products. $10 worth of powder and you're charged $90 is a wee bit more then what you're suggesting as not "particularly expensive". As to the contents of a bag of flour, well you get what you pay for and if you want some regular cooking flour, it'll be a combination of things, but if you bother to look up what is really there (it's on the side of the bag), you'll find you can get the raw materials in pure or nearly so states, for about the same price, though you will not likely find it of the shelf at the local grocery store. Online shopping is a big boon in this regard.

Originally Posted by soundman

. . .

Originally Posted by soundman

Talc is not particularly strong, does not sand particularly freely and is heavy in comparison to many other fillers . . .

Talc wouldn't be used in large quantities (per batch, comparative to other materials), nor as a glue, nor any of the other things you apparently think. Its use is to make a fillet "pull" smoothy, under a putty knife, plastic applicator or squeegee. Every single fillet blend available on the retail side, has a fair bit of talc in it, for the same reasons I'm suggesting the home builder use it.

Simply put, your conclusions are full of unsubstantiated assumptions and unfamiliar reasoning, not to mention any testing or data to support it, which doesn't do anyone any good. The last paragraph of my previous post pretty much sums it up, do try to keep up.

Just because there was no computer modeling done and the mix was arrived at by trial and error..........that holds true for 90% of first principles science and engineering (particularly materials science)......it does not mean that the filler blends where not "designed".

It is clear to anybody that has used various fillers that the resins perform very differently with different fillers and blends.

Ya don't need laboratory testing to see what is, "dogs balls obvious".

certain fillers clearly result in a heavy end product
certain fillers clearly result in a mechanically stronger end product
certain fillers clearly result in an end product that clearly sands more freely
certain filler clearly result in an end product that is clearly more abrasion resistant.

If you have played round with resins and variuos filler blends you will know which ones you like and what gets you the properties you need.

Commercially blended fillers are clearly mixed to specific ratios bassed on information known......they are designed....if they where not designed the ratios and the components would not matter.

That is before we mention anticaking and wetting agents that may be specific to particular resins.

I don't know what the market is like in the US....but here in Australia we buy our fillers seperately from our resins.

The two biggest factors in cost of fillers...all fillers..... are.
QUANTITY purchased
SUPPLIER.

But aint that true of all materials.


Remember too...much of the time you are not paying for the material but for the packaging and handling of the product...if you are buying in a 2 liter bucket...you are probaly paying $3 for the bucket, $1.50 for the lable and $5 for someone to fill the bucket and clean up the mess.

If I buy cotton and coloidal silica blend from a major woodowrking chain, I will pay nearly twice what I will pay from my local resin shop.....in the same quantities.

If I buy a 120gram bucket of blended filler ( about 800ml) it will cost me $15....another $4 will buy me 400grams or 2.2 litres in a bucket......if I buy a 2.5Kg bag about 10 litres it will cost me about $60

a 1kg bucket of industrial talc will cost me about $10

For those of us who are not engineers and do not buy various filler compoinents by the drum and do not have the knoweledge of the products needed and the mix ratios......buying a well known blended filler and buying well is good value and a very low cost compared to the cost of the resin.

If you think you are paying too much for filler...you need to shop better

cheers

Hi Guys
I know very little about epoxy fillers - but I do know a little bit about human behaviour.
It disturbs me on forums like this that people become fixated on the way they do things and sometimes become bent on proving that the way somebody else does things is wrong. This thread started out with Soundman and Par in broad agreement and is now morphing into something else.
I enjoy reading posts from both of you and respect both of you for your knowledge but at the end of the day if Par is happy to mix his fillers and Soundman is happy to buy his then why is it important for somebody to be right and somebody to be wrong ?
Lets keep the forum a nice place to visit.
Bgman

Originally Posted by PAR

. . . In the end, the only point is you don't have to be married to the retail products, but you do have to justify the added bother, of making and mixing up material combinations. For a one off boat just buy the packaged stuff, but if you do repairs or have a plan to build a few boats, you can save a good bit of money with these home made brews . . .

Couldn't agree more Bagman.

Originally Posted by bagman

Hi Guys
I know very little about epoxy fillers - but I do know a little bit about human behaviour.
It disturbs me on forums like this that people become fixated on the way they do things and sometimes become bent on proving that the way somebody else does things is wrong. This thread started out with Soundman and Par in broad agreement and is now morphing into something else.
I enjoy reading posts from both of you and respect both of you for your knowledge but at the end of the day if Par is happy to mix his fillers and Soundman is happy to buy his then why is it important for somebody to be right and somebody to be wrong ?
Lets keep the forum a nice place to visit.
Bgman

The whole thing comes down to PAR being sure he can further up the wall than everybody else and having the need to prove it......I know It does not matter how far I can up a wall..

cheers

Pissing up the wall is all well and good until you end up doing it like Todd Carney ! (those who don't follow the National Rugby League google Todd Carney and find out why this is a bad thing)

For a bloke who knows it doesn't matter, you're sure trying hard. If it makes you happy, go for it.