In winemaking, precision matters. Adding too much of an acid, tannin, or fining agent can't be undone and can drastically alter the balance of your wine. So how do commercial wineries make such precise adjustments without risking an entire vintage? The secret is a technique called a "bench trial."

A bench trial is a small-scale experiment where you test a range of addition rates on measured samples of your wine before treating the whole batch. It's the ultimate "measure twice, cut once" philosophy for winemaking. Mastering this simple, scientific process is one of the biggest leaps you can take toward making consistently great wine at home.

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For a complete list of fining agents and additive dosage ranges, be sure to download our Complete 70-Page Guide to Red Winemaking.

Why You Should ALWAYS Run a Bench Trial

Relying on the recommended dosage range on a product package is a gamble. Every wine is chemically unique and will react differently to additions. A bench trial removes the guesswork and allows you to:

• Avoid Over-Fining: Prevents stripping desirable flavors, aromas, and color from your wine.
• Perfect Your Balance: Lets you taste the exact effect of different acid or tannin levels to find the perfect balance.
• Compare Products: You can test multiple fining agents or tannins side-by-side.
• Prevent Costly Mistakes: A 15-minute trial can save you from ruining an entire batch of wine.

How to Conduct a Bench Trial: A 6-Step Guide

Let's walk through a common example: finding the right amount of a fining agent, like Bentonite, to clarify a hazy wine. The recommended range is 1-3 g/L.

Step 1: Determine Your Sample Volume

We recommend a sample size between 100 mL and 500 mL. For this example, we'll use 100 mL samples.

Step 2: Determine Your Dosage Range

It's a good idea to run 4-5 samples plus one untreated "control" sample. For our Bentonite example, a good range would be:

• Control: 0 g/L (no addition)
• Sample 1: 1.0 g/L
• Sample 2: 1.5 g/L
• Sample 3: 2.0 g/L
• Sample 4: 2.5 g/L
• Sample 5: 3.0 g/L

Step 3: Create a Model Solution

It's impossible to accurately weigh the tiny amount of powder needed for a 100 mL sample. The solution is to create a stock solution. A 10% solution is common.

How to Make a 10% Solution: Dissolve 10 grams of the additive into 100 mL of warm, chlorine-free water. Every 1 milliliter (mL) of this solution now contains 0.1 grams of the additive.

Step 4: Scale the Doses and Add to Samples

Now, do a little math to figure out how many mL of your stock solution you need for each sample. Use a graduated pipette for accuracy.

• Sample 1 (1.0 g/L) = 1.0 mL of solution
• Sample 2 (1.5 g/L) = 1.5 mL of solution
• Sample 3 (2.0 g/L) = 2.0 mL of solution
• Sample 4 (2.5 g/L) = 2.5 mL of solution
• Sample 5 (3.0 g/L) = 3.0 mL of solution

Step 5: Wait and Evaluate

Allow the trials to sit for the recommended time for the product to work. For fining agents, you'll be looking for which sample achieves the best clarity. For taste adjustments, you'll evaluate by sensory.

Step 6: Scale Up the Winner

Let's say you decide Sample 3 (2.0 g/L) gave you the perfect clarity. Now you can confidently treat your whole batch. If you have 5 gallons of wine:

• Convert gallons to liters: 5 gallons x 3.785 L/gallon = 18.9 L
• Calculate total addition: 18.9 L x 2.0 g/L = 37.8 grams of Bentonite needed for the full batch.

Conclusion

By taking the time to run a bench trial, you're not just following a recipe—you're making a calculated, informed decision that will result in a better, more polished final wine.

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