weighing high end epoxies

looking to mix several small batches of pro line epoxy and would love to know some of your methods for weighing small amounts. Do you prefer to spoon into cups on scale or ?

For accuracy using a scale is a must!

Measuring ProLine 4500 Epoxy using a 0.1 gram resolution scale.


(Example)
For mixing 20g of Epoxy.

Put your empty cup on the scale and zero it out.
Add epoxy resin to cup till you reach 20g.

Calculating Hardener: 20g + 16% = 3.2g of hardener needed.

Now while the epoxy is still on the scale pour (slowly) the hardener
in till the scale reads 23.2g

Mix well and use.

like your additive method. I've been doing it by two cups each weighed. figured a few of you have some better methods!

Gary T is right, for best results for small batches, a scale is a must. Preferably one that will read down to 0.1 gram.

Also as Gary mentioned. Mix well. I used to mix by hand, but now a chuck a craft stick (think small Popsicle stick) into my drill press and mix for a good minute. The more thoroughly the epoxy is mixed, the better assurance that it will perform to spec. At the end of mixing, there should be no streaks, just something that is homogenous in appearance.

Greg

Pour one into a cup, and use a syringe for the other.

If you are using super small amounts, you'll get more precision by pouring a fixed amount of hardener, then adjusting the amount of resin (larger proportion) based on that, and using a syringe to meter out that amount of resin.

If you are using large amounts, it's more convenient to pour a large amount of resin, then adjust the amount of hardener (smaller proportion), because filling a syringe 10 times is irritating, while 2 times is okay (for 5:1 epoxy).

great idea on measuring Gardner first- opposite what I do. great tip car vac!

I use these plastic weigh boats (different sizes, depending on amount needed)

https://www.ebay.com/sch/i.html?_od...p2045573.m570.l1313&_nkw=weigh+boats&_sacat=0

and a scale that measures to 0.1 g. I set up a spread sheet with two columns -- incrementing the first by 0.1 g for the resin (or hardener) and calculating the next to the nearest 0.1 g. I tare the weigh boat, add the resin (using pumps on the cans), record the weight, retare, and weigh out the amount of hardener shown on the spreadsheet printout (which I keep next to the balance). If you accidentally pump too much hardener you can add more resin by consulting the printout. Mix thoroughly in the weigh boat and apply.
NikeMikey

NikeMikey said:

I use these plastic weigh boats (different sizes, depending on amount needed)

https://www.ebay.com/sch/i.html?_od...p2045573.m570.l1313&_nkw=weigh+boats&_sacat=0

and a scale that measures to 0.1 g. I set up a spread sheet with two columns -- incrementing the first by 0.1 g for the resin (or hardener) and calculating the next to the nearest 0.1 g. I tare the weigh boat, add the resin (using pumps on the cans), record the weight, retare, and weigh out the amount of hardener shown on the spreadsheet printout (which I keep next to the balance). If you accidentally pump too much hardener you can add more resin by consulting the printout. Mix thoroughly in the weigh boat and apply.
NikeMikey

Click to expand...

These are what I used when I worked as a chemist and in school. What type of scale do you use?

GaryT said:

For accuracy using a scale is a must!

Measuring ProLine 4500 Epoxy using a 0.1 gram resolution scale.


(Example)
For mixing 20g of Epoxy.

Put your empty cup on the scale and zero it out.
Add epoxy resin to cup till you reach 20g.

Calculating Hardener: 20g + 16% = 3.2g of hardener needed.

Now while the epoxy is still on the scale pour (slowly) the hardener
in till the scale reads 23.2g

Mix well and use.

Click to expand...

OK, can someone get me straight on this, I thought I was good at math skills, but this has me perplexed. Is Proline a 5.5:1 or 6:1 epoxy? If 6:1, I can see where you'd use 16%. At 5.5:1 wouldn't you add 18% to the batch? 5:1 is 20%, I'm not discounting Gary's method, or I may be off on the ratio. He's mixed a heck of a lot more epoxy than I EVER will, just trying to get it straight.

I was in one of the big box food stores and bought a carton of aluminum foil sheets that are used in the food service business. They're probably about 8" square. Anyway, they were cheap and I put one of the scale everytime I weight epoxy and it's a great way to keep your scale clean.

Dave, I saw Gary's reply and it made me look up the 'ratios'. I see that he says to add...it looks like you need to multiply..read on

ProLine 4500 is 100 parts resin to 16 parts hardner 100/16 The 16% in Gary's reply is an easy way to figure out the hardner once you know the amount of resin. If I take 65 grams of resin and multiply it times 16%...that tells me I need 10.4 grams of hardner. That would make ProLine 4500 a 6.25-1 ratio.

ProLine 4100 is different. It calls for a 100/20 ratio 65 grams resin times 20% = 13 grams of hardner. Which is would make it a 5-1 ratio

If my math is right!

Tony

I use foam plates - zero the scale and then add either hardener or resin and then calculate the amount you need to add of other. zero again or just go to the target weight. I mix with a stick but I mix and mix and mix until it's mixed enough. The plate is useful because it doesn't concentrate the heat of reaction and speed up the cure. The stuff I work with has a good long working time but it's a best practice for when I switch to something with less of a pot life. It also helps me get the rollers I use to apply the stuff saturated evenly (when glassing a tube.)

I use a lot of epoxy, so I tend to use glue bottles. These are much like the ones that hobby store fast epoxy comes in, but much larger. When they run low I just add more from gallon containers. The bottles make weighing out easy. Just label them to keep track of what is what!

Epoxy cleans off scales easily with denatured alcohol before it is set. You can always wax the top of the scale and epoxy should come off easily enough even after setting.

Gerald

tfish said:

Dave, I saw Gary's reply and it made me look up the 'ratios'. I see that he says to add...it looks like you need to multiply..read on

ProLine 4500 is 100 parts resin to 16 parts hardner 100/16 The 16% in Gary's reply is an easy way to figure out the hardner once you know the amount of resin. If I take 65 grams of resin and multiply it times 16%...that tells me I need 10.4 grams of hardner. That would make ProLine 4500 a 7.25-1 ratio.

ProLine 4100 is different. It calls for a 100/20 ratio 65 grams resin times 20% = 13 grams of hardner. Which is would make it a 5-1 ratio

If my math is right!

Tony

Click to expand...

That makes sense....although proline 4500 is actually a 6.25:1 ratio(you may have typed it wrong). I tried to use search and saw something about the Proline was a 5.5:1 ratio, and that was what was confusing me. Thanks Tony(you have great youtube vids by the way).

The ProLine 4500 Epoxy was introduced to the rocketry community by Performance Rocketry a few years back. The mixing ratio of 16% came straight from the the manufacturer back then. Forget about all the XX:XX ratio's and just use the 16% formula. When you buy the epoxy from ProLine Rocketry the can says 16%, now that may vary depending on who you buy the epoxy from which might be where some of the confusion is coming from.

For me I use the 16% formula which works perfectly. Also it is recommended to NOT! use any type of additive what so ever when mixing the ProLine 4500. The 4500 is not a laminating epoxy and does not have the same absorption rate. Adding any type of filler will only weaken the epoxy.

thanks for all these great ideas! Will be doing a spreadsheet tonight. like it!

I use the same scale scale for mixing motors.
The easiest way for me is:
10 gram resin to 1.6 grams of hardener.
I keep the epoxy batches small to fit in paper cups.
Too much usually gets thrown out.


JD

I had never heard of boats until this thread. I had bought graduated cups for mixing- close, but not the same. so far it appears spooning epoxy or syringe for hardner

I use the West pumps in combination with a scale. As it turns out, the pumps can be used to get a pretty close mix for both the West epoxy and Aeropoxy (the two that I use the most). This is helpful in making large batches of epoxy. One benefit of the pumps is that you're not continually opening and closing bottles of epoxy, and the pumps minimize the air/moisture introduced into the containers. The main reason I use the pumps, though, is that you can lean on the pump to dispense the epoxy drop wise. So, I weigh out a little hardener, calculate how much resin I need, add resin using the pump to come up just a little short on the required amount, and then add dropwise to the exact weight. For example, if I'm 0.3 grams short on the resin, it's about 5 drops more to the exact weight. Piece of cake ...

Jim

I have just started using an epoxy from this supplier: https://www.astrochemical.com/

They are literally 5 miles from my house. Industrial product. I am using a 2:1 epoxy from them and so far so good. Data sheet attached.

View attachment AstroChemEpoxyResin.pdf

It would be too tempting to buy a 55 gallon drum. Then again, you could just buy more regularly.

When mixing epoxy and figuring out ratios, be sure to follow the ratio for the method you're using -- some epoxies are the same ratio whether by volume or weight, while others are one ratio by volume, and another by weight.

The hardener you use can also vary the ratio; as I recall, both West Systems and Fibreglast System 2000 use different ratios, depending on the specific hardener.

I do most of mine by weight -- I bought a small scale that measures to the 10th of a gram, for small batches, and I use a postal scale for larger.

For containers, I use mostly yogurt containers -- put it on the scale, tare it, then start measuring into the container. For larger batches, I'll use sour cream or cottage cheese containers. For the really big ones, it's an ice cream bucket.

One of these days, I'm going to buy some squeeze bottles, and use those to dispense. For now, though, I either drizzle out of the can, or use a popsicle stick.

-Kevin

While cleaning up my work area this morning, I realized just how much West System I am wasting. 4 Dixie bathroom cups with half-used batches were properly disposed. I will have a scale on order within the hour!

Cheers,
Michael

Free Mixing Table: Old thread... The suggestions were so good I created a table for my workbench. Waste is microscopic now! Thought I would share my Proline Mixing Grams Spreadsheet- you can solve in any direction! https://recabaren.com/assets/images/prolineepoxy.xls