Friday, March 10, 2023

3 Easy Ways to Measure a 2:1 Ratio Resin

Measuring resin can be challenging!

Have you ever struggled to get the right amounts of resin and hardener?

It's not so hard with a 1:1 ratio. But it's not so easy when your resin is a 2:1 ratio... or a 3:1 ratio. That's when it can be CONFUSING!

You probably know that if you get the measurements wrong, (or you don't mix thoroughly, or your room is too cold) you end up with resin that doesn't cure properly... it stays soft and bendy. Or worse, it stays sticky. And it ruins your whole project!

If this sounds like you, then you need an easy-to-understand method to work out how much of each part to pour out.

And I've got 3 methods for you to choose from!

But first, a little about ratios and what they actually mean. 

Your bottles of resin and hardener are marked with a ratio that's used to measure out the right amount of each part. It's different for every brand but most commonly, you'll find 1:1 and 2:1 ratios. The resin is Part A and the hardener is Part B.

In a 1:1 ratio epoxy, you need 1 part of Part A (the resin) and one part of Part B (the hardener).
In a 2:1 ratio, you need 2 parts of Part A and one part of Part B.

Now that you know what the numbers in the ratio mean, let's look at how to measure the right amount of each part.

Apart from your resin, you'll need cups with graduations marked on them so you have measurements to go by. For small amounts, these are my favourites. They have metric and imperial measurements on them so you can use whichever measurement you're most familiar with.

If you need larger cups, try these medium-sized cups that also have multiple measurements marked on them.

Method 1 - Multiplication 

If your resin is a 1:1 resin, then you just need to measure out equal parts of resin and hardener.
So let's skip the 1:1 and go to a 2:1 resin.

Most people find it easier to multiply numbers than divide them, so start by measuring out Part B, the hardener. The hardener is the ":1" part of the ratio.

Once you've poured this into a measuring cup, note the measurement and multiply the amount by 2. This is the "2:" part of the equation, the resin.

With a 3:1 ratio resin, you'll multiply by 3 for the resin. And so on.

This method is a simple way to get the right ratio of resin to hardener.

But what if you need to know the exact amounts of resin and hardener for your mould?

That's where this next method comes into play.

Method 2 - How to Work out the Exact Amount of Resin and Hardener to Fill Your Mould

This is an almost fool-proof method that only requires some simple maths to get it right. (I say ALMOST fool-proof because you still have to measure it accurately!).

The good thing is, this method works with any ratio of resin to hardener and it will work no matter how much resin your mould needs. 

For this method, you'll need to know two things:
With just these two things you can work out how much Part A and how much Part B to measure out to fill your mould exactly.

So let's start with an easy example. We'll use a 1:1 ratio resin and a mould that holds 210ml or 7oz of resin.

Now, follow the steps below:

Step 1: Add the two numbers of the ratio together.

For a 1:1 ratio, the sum is: 
1 + 1 = 2

The next step uses the volume of the mould. You can use either millilitres or ounces, whichever one you're most comfortable using.

Step 2: Divide the mould volume by the answer you got in Step 1, which is 2.

So that will be: 
210ml divided by 2 = 105
So the ":1" part of the ratio is 105ml 
i.e 105ml of hardener. 
The rest of the 210ml is the resin component (also 105ml).

Take a look at the chart below and follow the two simple steps. It's really quite simple when you break it down like this.

1 to 1 ratio calculation chart

OK, I know you need to see how it works in a different ratio, so let's look at a 2:1 ratio resin.

STEP 1: Add the two numbers of the ratio together: 2 + 1 = 3

STEP 2: Divide the mould volume by the answer: 210ml divided by 3 = 70ml

So the ":1" part is 70ml (the hardener) and the rest is the resin, the "2:" part of the ratio. 
You can check that by multiplying 70ml x 2 and you get 140ml. 
So 2:1 ratio will be 140ml resin/70ml hardener.

In a 3:1 ratio the sum would be:
3 + 1 = 4
210 divided by 4 = 52.5ml (hardener)
Multiply that by 3 = 157.5ml (resin)
Add the two numbers together and you have 210ml resin

And one last one just to show you it works for all ratios:
2.5 + 1 = 3.5
210 divided by 3.5 = 60 (hardener)
Multiply that by 2.5 = 150ml (resin)

You can also see the comparison with ounces in the chart below.
Resin calculation chart

If you measured your mould volume accurately, this method gives you enough resin to fill the mould without any wastage.

METHOD 3 - Using Calibrated Measuring Cups

Ratio measuring cups have all the ratio markings printed on the cups already. These can help you get the right proportions of resin and hardener. 

ratio paint mixing cup

When you use ratio cups, you don't have to do maths to get the ratio right.

All you have to do is pick the correct ratio on the cup for your resin kit and then measure the resin and hardener to the appropriate lines.

That seems simple enough... until you look at all the numbers on the cup. 

Talk about intimidating! 

There are dozens of lines and hundreds of numbers and it's confusing... how do you know which numbers to use?!!

Luckily, it's a whole lot SIMPLER than it first looks. If you isolate the ratio that you need, it's much easier to understand. 

First, let's look at the cup and see what markings are there. 

Around the top of the cup, you'll see the different ratios. Each ratio has 2 or more columns.
As well as the ratios, you'll see a column with volume measurements (in millilitres and fluid ounces). 

Tip: Some ratio cups have more than 2 columns for each ratio. If that's the case, you can totally ignore the extra columns. You only need the first two columns.

When using these cups, you need to know two things: 
  • how much resin you need for your project, and
  • the ratio of your resin system
Let's say you need 300ml (that's around 10oz), and your resin is a 2:1 system. 
ratio cup with 2to1 ratio highlighted

Find the 300ml mark on the cup and follow it around to the 2:1 ratio column. The number you need is in the second column (highlighted in light blue in the photo below). This is the amount of resin you'll end up with. On this cup, it's the number 4.

Now find the number 4 in the first column (highlighted in light pink) and pour out Part A to this line.

Part A and B measuring lines highlighted

Pour Part B to the number 4 in the second column.

You've now measured out 300ml of resin in a 2:1 ratio without doing any maths!

So even though it seemed daunting when you first looked at the cup, in the end, it's SO EASY!

These ratio cups are brilliant for larger quantities of resin. Just make sure you choose calibrated cups like these so that your proportions are right.

How to Work Out the Volume of your Mould

There's still one more thing to know about measuring resin and that's how to work out the amount of resin you need for your project.

All you need is a graduated measuring cup and some rice.

Fill the mould to the top with the rice. 
Pouring rice into the mould

Now pour the rice from the mould into the measuring cup. 

This is how much total resin you need to mix.

Pro Tip: Get yourself a journal and record how much each of your resin moulds holds. It's so handy to be able to refer to it each time you use the mould.

You can also work out the volume with water instead of rice but it's harder to pour the water from some moulds into the cup without spilling it. You also have to wait for your mould to completely dry before pouring resin into it!

If you'd like to see another method, watch this short video.

Pin These Tips for Later!
pouring resin in measuring cup

Happy Resining!

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