Ultra-small batch of epoxy

[Baltimore Lou]

I'm wondering if a drop of hardener is the same size as a drop of resin. If I need just a dab of epoxy for a super small job, and don't want to waste a couple of pumps worth, will I get a precise dose of each component if I can deliver just a drop of hardener to two drops of resin (my MAS epoxy is 2:1)? Thanks!

[Nicholas Scheuer]

Not familiar with viscosity of Mass. If the hardener and resin are different viscosity, you could try to measure by "volume" of the drop instead of merely by what drips off a stick or something.

I usually use a tad MORE hardener when mixing small doses, just to insure that it kicks. Probably not kosher, but I've always gotten away with it.

Moby Nick

[John Turpin]

I keep a big container of plastic spoons at my mixing table. I regularly need small batches and just use one of my mixing spoons for that. A plastic spoon is pretty shallow. I also mix 2:1. Three spoonsful of epoxy makes a very small batch and it always works fine. I can't imagine trying to mix a smaller batch than that.

[P.I. Stazzer-Newt]

For small batches - the epoxy glues which come in a welded-together-pair-of-syringes do a pretty good job..
http://cgi.ebay.co.uk/BRAND-QUALITY-ULTRA-STRONG-UHU-EPOXY-RESIN-GLUE-SYRINGE_W0QQitemZ260454505822QQcmdZViewItem?rvr_id =&rvr_id=&cguid=3f15b53b1270a0e20357ab47ff03960b

[kenjamin]

West System's G-Flex line of epoxy is a 1 to 1 mix so it's great for extra small batches.

[Thad Van Gilder]

I use syringes for that use.

-Thad

[Todd D]

I mix up small batches by weight. Every epoxy I have used gives the weight ratios for mixing on the label. West sells a small balance that reads to 0.1 gram. You can use it to mix a batch of epoxy that is under a gram. I have an old Sartorius lab balance that reads to 0.001g and I often mix very small batches for small jobs.

[AstoriaDave]

Baltimore Lou,

If you want, one way to proceed is to determine how many drops of each component will make up an ounce, or half an ounce -- whatever small volume you can accurately measure. Then use that and a little arithmetic to determine what number of drops of each will give you the 2:1 volume mixture needed. Measuring by weight is my preferred method, but if you don't want to mess with that, the above is about the easiest thing to do.

I would not expect the drop size to be the same for the two. And, in no case, would I purposely use more "hardener" than the other part. Epoxy is stronger and cures faster and better if it is accurately mixed.

[Baltimore Lou]

Thanks for all the interesting responses. I'd love to go the route of the lab scale for small batches. I'll have to keep my eyes open for one at yard sales, etc. The idea is not to waste epoxy/money, so I'd rather not make too much investment until I see myself doing enough of these micro-mixes to make it worthwhile. In the short run, I'll try the spoon idea. Sounds reasonable, but will still give me much more than I need, at least today, but certainly will only cost pennies.

[Robert W. Long]

We use a triple beam scale at the guitar shop and regularly mix small amounts of 5 to 1 west system by weight, it is actually better than mixing by volume for small amounts. Look for yard sales in crack house neighborhoods for a used one.

[Baltimore Lou]

Robert,
I'm in Baltimore, so that shouldn't be too much trouble...

[ahp]

When I need to make a repair or some little joint, I use Ace Hardware's epoxy that comes in small tubes. I squeeze out a drop or so on a piece of aluminum foil and an equal amount next to it and stir them together with a wood popsickle stick. It works.

[jgmarine]

Way Too small, use a stick, and 1: 2 eyeball the puddle diameter...? or Try gorilla glue....one part.

Jack

[pipefitter]

Extra small amounts are affected by the container and the mixing tool, meaning, in minute amounts, the percentage ratios of what gets left behind, that doesn't get included into the overall mix ends up being significant. Even with the 5 minute epoxy in the tubes, does not end up amounting to much by the time you move it around a little on whatever you are mixing in or on by the time you are done. I used to notice this when building fishing rods, where a small amount might be needed from time to time, resulting in tacky cures etc. Was always better off mixed in visibly measurable amounts.

[AstoriaDave]

What pipefitter said.

Transfer errors/losses will really mess up small batches. That's why you want to use a system that receives each component from the jug/pump and measures what is actually in the mix, not what was in the spoon.

That diameter business will also mislead you: a second drop which is twice the diameter of the first has FOUR times that in the first, because the amounts scale as the area of the drop, not the diameter.

[htom]

By volume is going to be tricky in tiny amounts. The drop size is constrained by surface tension of the drop, which I suspect is different for the two materials. Weight would be the way to go, into a tiny plastic bag which you'd then close and use to mix it in. Picking the least expensive MyWeigh at Old Will Knott's, http://www.oldwillknottscales.com/my-weigh-pointscale-150.aspx as an example; they sell other makes and other models, too, and have shipped early and correctly for me.

[ssor]

I use the puddle size method A 3/4 inch puddle is twice the size of a 1/2 inch puddle. just eyeball it, is close enough. I often use separate dip sticks for getting just a bit. Scrape off the excess back into the can. Open only one can at a time.

[DuncanvdH]

The smallest batch I did I think was (2:1 ratio) 20 grams resin and 10 grams hardener using an electronic scale. Tar button is so easy, but always keep an identical container present, because these electronic scales switch off when left alone for a couple of minutes....

[htom]

The 3/4" puddle is more than twice the 1/2" puddle (about 2.25). If you're going to do puddles, make three the same size. I don't know which order to make them in; I'd try to make two identically sized of hardener, and then one between those in size, of the resin, I suppose. You're still going to have problems because they will be of different heights. Plastic syringes are another possibility; ask your dentist for two of those disposables used for gum cleaning.

[Todd D]

Astoria Dave - I hope you don't do too many volume calculations.

Volume of a sphere is (4 x pi x r^3)/3 so volume scales as the cube of the radius. So your example of doubling the diameter of the drop actually increases the volume by a factor of 8 (2 cubed).

[Sven Heesterman]

I found this article http://www.duckworksmagazine.com/07/howto/scale/index.htm and made a scale. Really very nice for small batches up to one cup.

[Eric D]

good grief. Medicine dropper is damn accurate, use 2, one for each. Done.

If that is not good enough, drop it onto wax paper on the scale. One drop, note the weight, then add the hardener, one drop. weight, should be equal.

[keyhavenpotterer]

Plastic disposable syringes are made down to 1ml for the whole tube, so 0.2 for hardner and 1.0ml for epoxy is easy. have been using this method for years with no problems ever.

Example below

http://cgi.ebay.co.uk/Sterile-1-ml-Plastic-Disposable-Syringe-Pack-of-20_W0QQitemZ380165786446QQcmdZViewItemQQptZUK_BOI_ Medical_Lab_Equipment_Medical_Supplies_Disposables _ET?hash=item5883a58b4e#ht_500wt_1182

Brian

[SeaB]

So Brian, that's for 5:1 resin:hardner?

[Iceboy]

I second the syringes. I use veterinary syringes as they come in a little hard plastic case. I put them back in the case for short term storage and rinse them in vinegar and dry first for long term storage. If they get dirty or clogged I just toss them.

[AstoriaDave]

Astoria Dave - I hope you don't do too many volume calculations.

Volume of a sphere is (4 x pi x r^3)/3 so volume scales as the cube of the radius. So your example of doubling the diameter of the drop actually increases the volume by a factor of 8 (2 cubed).Todd, I think the person who suggested this method had two puddles on a flat surface, one twice the diameter of the other. Given similar average heights, the puddle of twice the diameter would have four times the material.

I agree spheres which differ by a factor of two in diameter would differ by a factor of 8 in volume, but I can not figure out how somebody would produce a drop, in the air, twice the diameter of another, let alone determine the diameters were in a ratio of 2 to 1. That seems impractical and improbable.

[Gerarddm]

What AHP said.

[ccx2]

What AHP said.
Wow, all this figgerin and syfrin seems a lot of trouble. I think i would just use a whole pump if thats what you have and be done with it. One shot out of a gallon of west would cost maybe 50 cent or so?:)

[ccx2]

Did not mean to put the quote in the above reply. Dont know how it got in there. :)

[Tom Robb]

Waste in small jobs is one of my peeves.
Single drop sizes? Why? What are you glueing that small that needs epoxy? How about super glue. My friend who's into RC airplanes uses it.
Measuring by weight with a cheap(ish) digital scale (diet/weight loss fans use them to measure food) is supposed to be trick.

[BillyBudd]

For my smallest of boat building needs, I use little clear plastic pots found at food establishments for holding self-serve condiments. Use a magic marker to draw a line indicating where you want your pour to stop. Empty the first pour (resin, for me) into the mixing pot, then refill the condiment pot twice for the hardener. I'll do as little as 1/4" as I mark it. Anything less is getting too fussy for me. A bit a waste is typically unavoidable but preferable to a poor mix.

[keyhavenpotterer]

So Brian, that's for 5:1 resin:hardner?

Yes, standard 5:1 West epoxy? You have me worried now.

My son's a vet so supply chain sorted. He will probably read this and ban me from his stock room!

I hate waste so I find mixing just what I need for any job and knowing it will go off properly works for me.

Brian

[Pacific Woody]

Might not help here, but for the procrastinators in the room, I put off many non-urgent epoxy jobs and just keep a list of them. Then, when I have a small job that needs epoxy now, I do that job and use the leftovers on the non urgent jobs. The 100 year old fir floor in my house is a prime candidate. Leftover epoxy is regularly poured into cracks in that floor.

[Sven Heesterman]

Waste in small jobs is one of my peeves.
Single drop sizes? Why? What are you glueing that small that needs epoxy? How about super glue. My friend who's into RC airplanes uses it.
Measuring by weight with a cheap(ish) digital scale (diet/weight loss fans use them to measure food) is supposed to be trick.

Super glue is not as resistant to long term water contact as epoxy and it may be way to quick to set.

[ssor]

I pay 75 cents for 12 cc syringes at my local farm supply. I can't push resin through the naaedles but they are great for maesuring small volumes.

[Baltimore Lou]

Wow, this question generated lots more response than I expected. Some really neat and creative ideas here. Thanks.

Tom Robb, to answer your question, every once in a while I find something like a small splinter or crack (or a post in my wife's earing) that needs to be epoxied. I realize that I could just use a pump of resin and a pump of hardener and be done with it, but I can't justify the waste. Actually, since I posted this I did find a very economical digital scale on ebay for all of $10, so I've ordered one. It should measure down to 1/10th of a gram. We'll see if it is a piece of junk. Sounds like it is made for the drug trade!

I also like Billy Budd's idea recently posted of marking small condiment cups from fast food places, calibrating them for mini-batches, but sometimes I'm literally thinking about a few drops.

Finally, I also agree with Pacific Woody: I try to keep a running list of jobs in and out of the shop that I need epoxy for, and hit them all in one batch. Unfortunately, my aging brain sometimes forgets the list until after i've added thickener...

[Bill Huson]

I use the WEST Small Batch Scale. For mix cups I recycle Milady's yogurt cups. The scale is a treat as for many years I just eyeballed the tiny mix. Never had a joint let go when eyeballing, which means either I had a good eye or WEST resin is very forgiving.

[ssor]

Now we come to the definition of an ultra small batch. Is it a few drops or a few cc's or an ounce or two? In the heavy industry that some of my friends work a few gallons is a small batch.

[Robert W. Long]

For me at the guitar shop a small batch is usually one gram of west system resin to 2/10s of a gram hardner dispensed with disposable pipettes, one for resin one for hardner, weigh the little plastic cup and dial that weight on the scale then add the epo. then readjust the scale and add the hardner. If your'e careful to scrape the sides of the cup and the mixing stick carefully the mix will be right on. This may sound anal, but 5 minute epo or 1 hour epo from the hardware store sucks for strength compared to west or system 3.

[P.L.Lenihan]

pipefitter has it right.Too small and you begin to lose due to the stir stick soaking up some,some lining the walls/surface of the mixing container etc etc.

My little helper and I prefer these graduated cups for so called small "batches"................

http://im1.shutterfly.com/media/47a0df30b3127ccef943e58be2c700000050O02BauGzJmyZA9 vPgo/cC/f%3D0/ps%3D50/r%3D0/rx%3D720/ry%3D480/

Cheap at the pharmacy by the package.



Cheers!


Peter

[P.I. Stazzer-Newt]

Waste in small jobs is one of my peeves.
Single drop sizes? Why? What are you glueing that small that needs epoxy? ....

Buzzers and the like... on a 14 or 16
http://i54.photobucket.com/albums/g88/cowieuk/sbs1/a016.jpg

http://www.flyforums.co.uk/fly-tying-step-step/27121-epoxy-bubble-corixa.html

[RodB]

http://im1.shutterfly.com/media/47a0df30b3127ccef943e58be2c700000050O02BauGzJmyZA9 vPgo/cC/f%3D0/ps%3D50/r%3D0/rx%3D720/ry%3D480/


pipefitter has it right.Too small and you begin to lose due to the stir stick soaking up some,some lining the walls/surface of the mixing container etc etc.

My little helper and I prefer these graduated cups for so called small "batches"................

These 1 oz medicine cups are available all over...and for 2:1 mixes...you can mark 1/8 oz, and 3/8 oz... put hardener in first.... then fill to 3/8.... stir with a small stick... done! If you stir with a piece of those BBQ shisKabob sticks... I have found you have enough total mixture to have very consistent results with the epoxy.

For smaller amounts of special needs...I use syringes (if I know I have some small epoxy uses coming up), and by the way, usually a 10CC syringe. Just fill one with resin, one with hardener... quite easy to measure out by the CC. If you can get some 18 gauge needles, epoxy will go thru them fine. I use them to inject epoxy into cracks or into holes.

RodB.

[Pacific Woody]

PI, in British Columbia we call that a boatman. I don't use epoxy on small flies, too easy to replace anyway so head cement or nail polish does the job. Nice tie all the same.

[Tom Robb]

I'd have supposed that neither an earing post nor a dry fly benefit all that much from epoxy unless you're manufacturing them on an industrial scale.