Simple way to measure epoxy

[JEM]

This demonstration and others can be found at http://jemwatercraft.com/forum/viewforum.php?f=7

Epoxy is made of 2 parts: Resin and Hardener. Most epoxies call for a 2:1, 3:1, or 5:1 ratio of Resin and Hardener.

One way to measure the appropriate amount to use metering dispensing pumps that are offered by many suppliers. Another method is using a graduated measuring cup.

These pumps typically are very reliable but they do break down after a while and let air into the pump. This causes the pump to "burb" and give an inaccurate amount of Resin or Hardener. So if you don't have reliable metering pumps or just want to use a more visual method, here's an easy way that doesn't require using pumps (or purchasing graduated measuring cups).

Helping in the demonstration is our 8-year old assitant who happens to be the "E" in JEM (JEM Watercraft). :D

Please note: This method shows how to mix a small amount of epoxy with a 2:1 Resin-to-Hardener ratio. This can be adjusted for more epoxy or different ratios.

You'll need some clear plastic cups and a permanent marker.

http://www.jemwatercraft.com/images/Tutorial/Resin/MeasureA.jpg

Place one cup inside another.

http://www.jemwatercraft.com/images/Tutorial/Resin/MeasureB.jpg

Decide how much total epoxy you want to mix at one time. In this example, we selected about 1/2 of the plastic cup.

With the marker, draw a line on the outer cup. Label it "H" for Hardener.

For a 2:1 ratio, you have 3 total parts: 1 part Hardener and 2 parts Resin. So we marked our line about 1/3 up toward half the cup. If your epoxy is 3:1, then you'll have 4 total parts. Mark about 1/4 the way up.

http://www.jemwatercraft.com/images/Tutorial/Resin/MeasureC.jpg

In this next part, we use water. Much cheaper and easier to clean up if you make a mistake.

With an empty cup still inside the marked cup, fill to the marked line.

http://www.jemwatercraft.com/images/Tutorial/Resin/MeasureD.jpg

Remove the inner cup and set aside. Measure 2 more parts so you have a total of 3 equal parts.

http://www.jemwatercraft.com/images/Tutorial/Resin/MeasureE.jpg

Place a cup back inside the marked cup, and pour the 3 equal parts into the cup.

http://www.jemwatercraft.com/images/Tutorial/Resin/MeasureF.jpg

Mark another line on the cup and label it "R" for Resin.

http://www.jemwatercraft.com/images/Tutorial/Resin/MeasureG.jpg

So when your ready to mix, first fill the inner cup with Hardener up to line H, then fill with Resin to line R. Remove the inner cup and mix. Save the marked cup for the next batch.

http://www.jemwatercraft.com/images/Tutorial/Resin/MeasureH.jpg
Easy! :D

[Lignum]

well ill be buggered:D what a great idea. Top stuff:D :D :D

[Harry72]

Handy hint of the week?

[Boatmik]

Good method.

I generally use a baked bean tin *burp* because it is parallel sided.

Mark a stick with the epoxy ratios.

So if it is 2 to 1

Mark the stick with a mark (pencil or saw kerf) two inches from the bottom end. Do a mark one inch above that.

Put stick in tin.

Pump or pour resin in up to the first line - then hardener up to the second - and you are off.

The only labour is to mark the stick.

The method above looks better for very small quantities though where the stick gets hard to see and pumps just don't figure at all.

MIK

[HelloMcFly]

This seams like a great idea at first glance. However, Boatmik raises a good point because the sides of the cups are not parrallel.

The distance between the bottoms of the two cups means that you'll actually be introducing an error into the ratio. Especially since there is more volume as you move up the sides of the cups.

To reduce errors, you should use only two cups:

Add an amount of water to cup #1
Mark the water level - with an H on Cup #1
Pour the water from Cup #1 into Cup #2
Fill Cup #1 to the H Line and Pour into Cup#2
Repeat step 4 for the ratio required. (A 3:1 ratio would require that you repeat step 4 three times - 5:1 would require 5 refills - etc.)
Pour all of the water from Cup #2 back into Cup #1 and mark the water level with an R
Pour out the water in Cup #1 and thoroughly dry it with a paper towel.
Use Cup #1 to measure your epoxy.
Of course, you could mark several cups with the H amount and then use the final amount in cup #2 to mark all of the R's. Of course, the thoroughly drying part is very important! :roll: You don't want to add water to you epoxy!

This is a great idea, so I'm not trying to be mean or anything. However, I am building a fiberglass airplane in my garage (http://www.quickheads.com/construction-log/). This means that the epoxy ratios are very critical. I found this post while searching for ratioing methods and thought I would add my two cents.

The method above would work fine for woodworking I'm sure. Unfortunately, some people who use epoxy will need to be VERY accurate when measuring.

I hope this helps some of them out.

Warm regards,
Dan Yager
www.quickheads.com (http://www.quickheads.com)

[aus_stevo]

Good method.

I generally use a baked bean tin *burp* because it is parallel sided.

Mark a stick with the epoxy ratios.

So if it is 2 to 1

Mark the stick with a mark (pencil or saw kerf) two inches from the bottom end. Do a mark one inch above that.

Put stick in tin.

Pump or pour resin in up to the first line - then hardener up to the second - and you are off.

The only labour is to mark the stick.

The method above looks better for very small quantities though where the stick gets hard to see and pumps just don't figure at all.

MIK

I never trust the pumps, just dont. only takes being caught out once to put me off for life.

the next step is to use your old broken tape measures as the stick. pre graduated and dont drop any crap in the resin. cut them with an old pair of scisors every 200mm.

it gets a bit exiting with some resins though, SP/Gurrit make a high tech resin with ratio of 100:28 (ampreg22, for those playing at home)

[anewhouse]

For even smaller amounts, there is another method that has served me and a lot of other kayak builders well.

Store the resin and hardener in different coloured plastic picnic sauce bottles, the ones with the tall nozzle on top.

Use a plastic syringe to plug the nozzle.

To measure the resin or hardener, just invert the bottle and draw out the resin the way the doctors do.

It is possible to accurately measure amounts as small as 1 or 2ml with this method.

The syringe just stays in the nozzle to seal the bottle.

It works well for building something the size of a kayak, but is not a technique I would use for something as big as a yacht.

[igatenby]

I use parallel-sided Ski yohgurt tubs and paddlepop sticks and a pencil.

For mixes up to and including one tub (200g) I mark a pencil line for the amount of mix I want, then I mark the resin level below that. I use mainly 5:1 mix, sometimes 2:1.

For 5:1 - I draw the top line (full mix) another line at half that, then divide the top section into equal thirds. It takes about 2 seconds to do and is accurate. Its even easier for 2:1 - top line then into thirds... three lines total.

I keep two or three of these yoghurt containers on the go - I mix the resin/hardener in them then pour the mix into another container (usually a chinese takeaway, or other plastic tub that is no good for mixing ratios (non-prallel sides) for mixing with microbaloons or fibre - then set the yoghurt container on a level bench. The dregs settle into the bottom and give a dead level bottom to the container.

For larger mixes... a little maths is needed. Three tubs = 2 1/2 of resin, 1/2 of hardener.

I've made thousands of mixes this way - hundreds of litres of epoxy and never had a failure. I used the West pumps about twice, had a burp failure and threw them away.

2 seconds.... vs failure and complexity.

I like the fast, accurate, easy way

[b.o.a.t.]

I just use 2:1 BoteCote so that minor errors with the pumps aren't critical. :U

for very small batches - 1 or 2 teaspoons - I use Mk.1 eyeball on the blob size
in the bottom of the pot.

Larger batches - up to 150ml or so - I try to keep count of the pumps, cross-
checking with a careful Mk.1 eyeball guesstimate of the relative volumes.
If I lose count of the pumps, it sometimes helps to re-calibrate the Mk.1
eyeball with a glass of wine.

Over ~150ml... I don't do them - too much like hard work to beat it going
off in the pot. Anyway, kayaks are only little boats... :2tsup:

Burp errors are easily corrected with a little extra blop from the offending pump.

So far, no failures, although there is often a bit of hardner left in the bottom
of the bottle when the resin bottle runs out. Or vice versa. I like to think that
is due to dispenser error at the factory. :D

Good stuff the old BoteCote. Tolerates even rough-as-guts users like me. :D :2tsup:

Oh, and I disagree about JEM's method being inaccurate.
The second marker is set at a -measured by volume- height above the first.
Though they be cheap, plastic cups are produced to within a flyspeck of being perfectly identical.
The difference in position, and therefore accuracy between any two inner cups would
likely need a micrometer to measure. Therefore would have insignificant impact on
the ratios. In fact, it is likely that the thickness and crookedness of the fill marker lines
would introduce greater errors than cup differences.

I would think that an epoxy which is -that- sensitive to ratio variations would need to
have some unique & extraordinary properties to make it worth the hassle for the vast
majority of users & applications. Certainly not to this little black duck anyway !!

So, I have to ask, how fussy is your epoxy, really ?

cheers
AJ

[bloggs1968]

Here's what we use in our workshop.

We use a very simple sytem with WEST as it can be meausred by weight. On the door of the hot box is a weight chart and on the chart it shows the amount of resin and the amount of hardener in grams needed for a particular quantity of mixed resin. The chart runs in 50 gram increments to 200 grams then 100 gram increments to 1kg. Electronic postal scales are ideal for this (on ebay for about 20-25 bucks).

For mixing containers, go to any food packaging supplier and buy a box of BS20 or BS30 round take away food containers. You can buy them by the sleeve of 50 or by the box ( about 50-60 bucks for 500)The BS30's weigh 19grams and this is used as a check weight to see if the scales are reading correctly before zeroing the scales.

Another advantage of going be weight is that if you keep a usage sheet for all of your mixes and what they have been used for, you will end up saving heaps of time and epoxy. For example, if you are planking a clinker ply boat and you know that you mixed 200 grams of thickened epoxy to hang the second plank but it only took 150 grams to do the job then when you go to fit the next plank you can go ahead and mix the correct amount of resin first time with little or no waste at all.

AD

[Darce]

This seams like a great idea at first glance. However, Boatmik raises a good point because the sides of the cups are not parrallel.

The distance between the bottoms of the two cups means that you'll actually be introducing an error into the ratio. Especially since there is more volume as you move up the sides of the cups.


To reduce errors, you should use only two cups:
Add an amount of water to cup #1
Mark the water level - with an H on Cup #1
Pour the water from Cup #1 into Cup #2
Fill Cup #1 to the H Line and Pour into Cup#2
Repeat step 4 for the ratio required. (A 3:1 ratio would require that you repeat step 4 three times - 5:1 would require 5 refills - etc.)
Pour all of the water from Cup #2 back into Cup #1 and mark the water level with an R
Pour out the water in Cup #1 and thoroughly dry it with a paper towel.
Use Cup #1 to measure your epoxy.
Of course, you could mark several cups with the H amount and then use the final amount in cup #2 to mark all of the R's. Of course, the thoroughly drying part is very important! :roll: You don't want to add water to you epoxy!

This is a great idea, so I'm not trying to be mean or anything. However, I am building a fiberglass airplane in my garage (http://www.quickheads.com/construction-log/). This means that the epoxy ratios are very critical. I found this post while searching for ratioing methods and thought I would add my two cents.

The method above would work fine for woodworking I'm sure. Unfortunately, some people who use epoxy will need to be VERY accurate when measuring.

I hope this helps some of them out.

Warm regards,
Dan Yager
www.quickheads.com (http://www.quickheads.com)


Oops, he missed the point of marking on the outer cup. Jem's use of an outer cup to mark the ratios and then placing the mixing cup inside it before pouring the goo means it's irrelevant wether the sides are parallel or not. They just have to be the same size.

Sometimes the simplest methods are the cleverest - nice idea Jem:2tsup: