Most people who work with Deep Pour epoxy resin measure their components by volume using mixing cups. That works perfectly for small projects. But there is something that not everyone knows: for large pours like river tables, measuring by weight is faster, more accurate, and significantly easier to manage. And Craft Resin Deep Pour fully supports this approach.
Expert collaboration: This guide was created with Alex from blueprint_woodcraft, a professional woodworker and resin maker who builds river tables and large epoxy projects in his workshop. His hands-on method is the foundation of the calculations, ratios, and workflow explained below.
Watch both videos before you start your next large project:
Expert video guides: Before starting your next large Deep Pour project, watch Alex’s two practical video guides:
-
How to Calculate the Right Amount of Epoxy Resin for a River Table
Learn how to measure length, depth, and average river width to estimate the total epoxy volume. -
How to Convert the Mixing Ratio from Volume to Weight for Deep Pour Epoxy
See how Alex converts Craft Resin Deep Pour’s 2:1 volume ratio into a practical weight-based workflow.
In this guide, you’ll learn:
- Why measuring by weight is better than volume for large epoxy pours
- How to convert the Craft Resin Deep Pour 2:1 volume ratio to a precise weight ratio
- Step-by-step calculation for how much resin you need for a river table
- Complete reference tables for weight mixing at every project scale
- Expert tips from Alex at blueprint_woodcraft
- FAQ and further reading
Why Volume Measuring Breaks Down on Large Projects
For coasters, jewelry, or small molds, measuring cups work perfectly. The volumes are small, the process is quick, and a standard graduated cup gives you everything you need.
River tables are a different situation entirely. When a single project requires 15 to 20 litres of epoxy mix, measuring by volume becomes impractical fast. As Alex puts it: "The table I poured needed 16 litres of epoxy. Imagine trying to measure that using small mixing cups. I would need about 16 of those, trying to replicate the colour and wasting time constantly mixing in those small cups."
Measuring by weight on a digital scale solves all of this. You place a bucket on the scale, add the required amount of resin, then add the required amount of hardener directly into the same bucket. One container, one scale, one clean workflow. No multiple cups, no repeated colour mixing, no risk of measurement error accumulating across many small batches.
It is also more precise. A digital scale accurate to 1g eliminates the parallax errors and inconsistencies that come from reading liquid levels in measuring cups, especially when the volumes are large and the stakes of an incorrect ratio are high.
The Key Insight: Volume and Weight Are Not the Same
Here is the part that trips people up. Craft Resin Deep Pour has a 2:1 mix ratio by volume. That means two parts resin to one part hardener, measured as volumes.
If you simply apply that ratio to weight - 200g resin to 100g hardener - the chemistry shifts slightly. The reason is density. Resin and hardener are different substances with different densities. They do not weigh the same per millilitre. Measuring equal volumes gives you the correct chemical ratio because volume is what the formulation is designed around. Measuring equal weights does not, because the two components have different weights per unit of volume.
This is a well-understood principle in stoichiometry, the chemistry of mixing components in correct proportions. When you switch from volume to weight, you need to compensate for the density difference between resin and hardener to preserve the correct chemical ratio.
As Alex explains: "Because the resin and the hardener do not weigh the same per millilitre, measuring by weight without adjusting the ratio would slightly change the chemistry of the mix."
The Weight Conversion Rule for Craft Resin Deep Pour
Alex has developed a simple and practical conversion rule for Craft Resin Deep Pour specifically. The standard ratio is 2:1 by volume. When measuring by weight, the adjusted ratio is:
For every 100g of resin, use 45g of hardener
This small reduction in hardener compared to the pure 50g you might expect compensates for the density difference and brings the mix back to the correct 2:1 volume chemistry.
| Method | Ratio | Best used for |
|---|---|---|
| By volume | 2 parts resin : 1 part hardener | Standard measuring with graduated mixing cups |
| By weight | 100g resin : 4g hardener | Large Deep Pour projects measured on a digital scale |
| By percentage | 68.97% resin : 31.03% hardener | Calculating any custom batch size by total weight |
This ratio applies specifically to Craft Resin Deep Pour. Different epoxy brands have different component densities, so always check whether the same adjustment applies to other products before using this method.
Part 1: How to Calculate How Much Resin You Need
Before you can measure anything, you need to know your total volume. For a river table, this requires three measurements: length, depth, and average width.
Step 1: Measure the length
Measure the full length of the river from one end of the table to the other. This is a single straightforward measurement along the longest axis of the pour.
Step 2: Measure the depth
Measure the depth of the cavity where the resin will sit. Again, a single measurement taken at a representative point in the pour.
Step 3: Calculate the average width
This is the step most people get wrong, and it is the most important one. Unlike the length and depth, the width of a river table is not consistent. The slabs have a natural live edge, and the shape moves in and out across the length of the table.
As Alex explains: "The width is not consistent. The river moves in and out because the slabs have a natural live edge. The shape is wavy and irregular."
The correct method is to take multiple width measurements along the full length of the table. For a standard dining table, take 10 to 12 measurements spaced evenly from one end to the other. Add all the measurements together and divide by the number of measurements. The result is your average width.
Step 4: Calculate the volume
Multiply length by average width by depth. If you are measuring in centimetres, the result is in cubic centimetres (cm³), which is the same as millilitres.
Volume (mL) = Length (cm) x Average Width (cm) x Depth (cm)
To convert to litres, divide by 1,000.
Step 5: Add a 10% buffer
Always add 10% to the calculated volume to account for measurement imprecision, material lost during mixing, and any unexpected variations in the pour.
Total volume with buffer = Calculated volume x 1.1
Part 2: Converting Volume to Weight
Once you have your total volume in litres, convert to approximate weight for planning purposes. Craft Resin Deep Pour has a density of approximately 1.1 g per mL when mixed. This means:
Weight in grams = Volume in mL x 1.1
Or more simply: for rough planning, treat 1 litre of mixed resin as approximately 1.1 kg.
Alex's calculation example
Alex's river dining table required the following calculation:
| Measurement | Value |
|---|---|
| Length | Measured in cm |
| Average width | 10 to 12 measurements, averaged |
| Depth | Measured in cm |
| Calculated volume | Approximately 13.5litres |
| Volume with 10% buffer | Approximately 15litres |
| Total weight estimate | Approximately 15kg |
| Resin needed | 10kg 750g |
| Hardener needed | 4kg 840g |
| Total mix | Approximately 15kg 590g |
Part 3: Calculating Resin and Hardener by Weight
Once you have your total mix weight, use the 100:45 ratio to split it into resin and hardener amounts.
Resin = Total weight × (100 / 145)
Hardener = Total weight × (45 / 145)
Or in percentage terms:
Resin = Total weight × 0.6897
Hardener = Total weight × 0.3103
Quick Reference: Weight Mixing Table for Craft Resin Deep Pour
Use this table to find your resin and hardener amounts directly without calculating from scratch. All values use the adjusted 100:45 weight ratio.
| Total mix needed | Resin | Hardener |
|---|---|---|
| 500g | 345g | 155g |
| 1kg | 690g | 310g |
| 2kg | 1,380g | 620g |
| 3kg | 2,069g | 931g |
| 5kg | 3,448g | 1,552g |
| 7kg | 4,828g | 2,172g |
| 10kg | 6,897g | 3,103g |
| 12kg | 8,276g | 3,724g |
| 15kg | 10,345g | 4,655g |
| 18kg | 12,414g | 5,586g |
| 20kg | 13,793g | 6,207g |
| 25kg | 17,241g | 7,759g |
Volume to Weight Reference: How Much Resin Do You Need?
Use this table to estimate total mix weight from your calculated volume.
| Calculated volume (litres) |
Volume with 10% buffer |
Approximate total weight |
|---|---|---|
| 2L | 2.2L | 2.4kg |
| 4L | 4.4L | 4.8kg |
| 6L | 6.6L | 7.3kg |
| 8L | 8.8L | 9.7kg |
| 10L | 11L | 12.1kg |
| 12L | 13.2L | 14.5kg |
| 14L | 15.4L | 16.9kg |
| 16L | 17.6L | 19.4kg |
| 18L | 19.8L | 21.8kg |
| 20L | 22L | 24.2kg |
Step-by-Step: How Alex Mixes Deep Pour by Weight in the Workshop
Here is the full process as Alex applies it on real projects.
- Calculate total mix needed. Use the river dimensions to calculate volume, add 10% buffer, and convert to approximate weight using the tables above.
- Divide into batch sizes. As Alex notes: "Even 15 kg of resin, I would not be able to mix in one bucket." Large pours should be divided into separate batches mixed in equal parts. Decide your batch size before you start and plan how many mixes you need to reach the total.
- Place the bucket on the scale and zero it. Tare the scale with the empty bucket so the bucket weight is not counted.
- Add the resin. Pour the calculated resin weight into the bucket. For a 5 kg batch: add 3,448g of resin.
- Add the hardener. Without removing the bucket from the scale, add hardener directly on top of the resin until the scale shows the total mix weight. For a 5 kg batch: add 1,552g of hardener to reach a total of 5,000g in the bucket.
- Mix thoroughly. Mix slowly for 3 to 5 minutes, scraping the sides and bottom of the bucket on every pass. Do not rush the mixing regardless of how large the batch is.
- Add pigments if needed. Add pigments after the base mix is fully combined. Mix again briefly until colour is uniform.
- Pour while at full fluidity. Deep Pour has a working time of 90 to 100 minutes. Pour while the resin is still fully liquid for the best bubble release and flow around inclusions.
Expert Notes from Alex at blueprint_woodcraft
“Most epoxy manufacturers give their mixing ratio by volume. For large pours, measuring by volume is often not practical. When you are building something like a river table, the volumes become much larger. It is much easier to work by weight using scales. It is faster, more precise, and much more practical for large-scale projects.”
“By reducing the hardener slightly when measuring by weight, we bring the mixture closer to the original 2:1 volume ratio. The resin and the hardener do not weigh the same per millilitre, so this adjustment compensates for the difference in density.”
“Once the calculation is done, the whole process becomes very straightforward. I place the bucket on the scale, add the required amount of resin, then add the required amount of hardener, mix everything thoroughly, add pigments, and the epoxy is ready for the pour.”
“An incorrect mixing ratio can lead to many problems like soft, not fully curing resin or flash cure. Taking a few minutes to calculate everything properly can save you a lot of trouble later.”
Important Notes Before You Use This Method
This ratio is specific to Craft Resin Deep Pour. Different epoxy brands have different component densities. The 100:45 weight adjustment is based on Alex's practical experience with Craft Resin Deep Pour specifically. If you use a different brand, check whether the same adjustment applies or contact the manufacturer.
Always mix in manageable batches. Even with accurate weight measurements, mixing too much resin at once increases the exothermic heat and reduces the quality of the mix. Split large pours into equal batches and mix each one separately before combining in the mold.
Pour depth limits still apply. Measuring by weight does not change the pour depth limits. Craft Resin Deep Pour can handle up to 6 cm per layer on wide, open molds. For narrow molds, reduce the depth per layer to manage heat buildup. For more detail on planning your pour depth and heat risk, read our Deep Pour formula guide.
This method does not apply to Arts and Crafts or Table Top resin. Arts and Crafts and Table Top resin both use a 1:1 ratio by volume. For these formulas, measuring by volume with graduated cups remains the recommended approach.
Quick Recap
Before every large Deep Pour project, keep these points in mind:
- Measuring by weight is faster and more accurate than volume for large pours
- The adjusted weight ratio for Craft Resin Deep Pour is 100g resin to 45g hardener
- Calculate river volume using length, average width (10 to 12 measurements), and depth
- Always add 10% to the calculated volume before converting to weight
- Divide large total volumes into equal batches and mix each one separately
- Mix thoroughly for 3 to 5 minutes per batch regardless of batch size
- Pour depth limits of 6 cm per layer still apply regardless of mixing method
FAQ: Mixing Craft Resin Deep Pour by Weight
Can I mix Craft Resin Deep Pour by weight instead of volume?
Yes. Craft Resin Deep Pour can be measured and mixed by weight for large projects where measuring by volume is impractical. Use the adjusted ratio of 100g of resin to 45g of hardener to compensate for the density difference between the two components.
Why is the weight ratio different from the volume ratio?
Resin and hardener have different densities. They do not weigh the same per millilitre. Applying the 2:1 volume ratio directly to weight would slightly change the chemistry of the mix. Reducing the hardener from 50g to 45g per 100g of resin compensates for this difference and preserves the correct chemical balance.
How do I calculate the average width of a river table?
Take 10 to 12 width measurements spaced evenly along the full length of the table. Add all measurements together and divide by the number of measurements. The result is your average width, which accounts for the natural irregularity of a live edge slab.
How much extra resin should I calculate to account for waste?
Add 10% to your calculated volume before converting to weight. This buffer accounts for measurement imprecision, material remaining in buckets and mixing tools, and small variations in the actual pour dimensions.
How do I split a large pour into batches?
Divide the total mix weight into equal batches small enough to mix comfortably in a single bucket. Mix each batch separately and pour them one by one. Keep batches consistent in size to ensure consistent colour and chemistry across the full pour.
Does this method change the curing time?
No. The adjusted weight ratio produces the same chemical mix as the standard volume ratio, so curing time is not affected. Craft Resin Deep Pour cures to tack-free in 24 to 36 hours and reaches full cure in 72 to 96 hours at the recommended temperature of 70 to 80°F / 21 to 27°C.
Can I use this weight method for Arts and Crafts or Table Top resin?
This guide is specifically for Craft Resin Deep Pour. Arts and Crafts and Table Top both use a 1:1 ratio by volume, and for those formulas measuring by volume with graduated cups is the standard and recommended approach.
Further Reading and Watching
For more on planning large Deep Pour projects, calculating resin volume, mixing ratios, and avoiding curing problems, these resources will help you continue from this guide.
Ready to Mix Deep Pour by Weight?
Once you have calculated your river table volume and converted it into resin and hardener weights, the final step is choosing the right kit size for your project. Smaller pours may only need a compact Deep Pour kit, while large river tables are usually easier to plan with larger gallon sizes.
Shop Craft Resin Deep Pour by size:
- Craft Resin Deep Pour Epoxy 1,5L
- Craft Resin Deep Pour Epoxy 6L
- Craft Resin Deep Pour Epoxy 12L
- Craft Resin Deep Pour Epoxy 22,8L
Choose the size that matches your calculated total mix, add your 10% buffer, and always measure carefully before pouring.
