In many laboratories, pre-wetting pipette tips is part of standard pipetting technique.
In others, it’s often skipped to save time.
So which is correct?
Is pre-wetting really necessary, or is it simply a habit passed down through lab training?
The answer lies in understanding how pipettes actually move liquid — and why the inside surface of a pipette tip matters more than most people realize.
What Is Pre-Wetting?
Pre-wetting is the process of aspirating and dispensing the same liquid once or several times before performing the actual pipetting step.
This simple action coats the inner wall of the pipette tip with the sample liquid.
While it may seem trivial, this step stabilizes the liquid behavior inside the tip and improves measurement consistency.
Why Dry Tips Can Cause Errors
Most pipette tips are made from polypropylene.
Even though the material is smooth, a completely dry tip can interact with liquids in ways that affect volume accuracy.
When the first aspiration occurs in a dry tip:
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Liquid may partially adhere to the inner wall
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Surface tension affects the sample distribution
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The internal air cushion stabilizes more slowly
As a result, the first aspirated volume may be slightly smaller than intended.
This effect becomes more noticeable when working with small volumes.
When Pre-Wetting Matters Most
Pre-wetting is especially beneficial in the following situations:
Low-volume pipetting
At volumes such as 1–10 µL, even tiny variations can significantly affect results.
Viscous solutions
Liquids such as glycerol, buffers with high protein content, or enzyme solutions tend to cling to surfaces.
High-precision assays
Applications like PCR setup, qPCR preparation, or enzyme assays require consistent volume delivery.
Repetitive dispensing
Pre-wetting stabilizes conditions for repeated pipetting of the same reagent.
In these cases, skipping pre-wetting can introduce unnecessary variability.
When It May Be Less Critical
In routine laboratory work involving larger volumes, the effect of pre-wetting may be minimal.
For example:
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Pipetting 100 µL or more
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Handling simple aqueous solutions
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Non-critical sample transfers
However, even in these cases, pre-wetting can improve consistency between replicates.
Many laboratories include it in their standard pipetting technique for this reason.
How to Perform Pre-Wetting Properly
Pre-wetting is simple and only takes a few seconds.
A common approach is:
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Aspirate the liquid into the tip
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Dispense it back into the original container
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Repeat one to three times
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Perform the actual aspiration for measurement
This allows the liquid to condition the tip surface and stabilize the air cushion inside the pipette.
The Balance Between Speed and Accuracy
In high-throughput labs, skipping pre-wetting may save a few seconds per operation.
However, the time saved can quickly disappear if inconsistent pipetting leads to repeated experiments or unreliable results.
In many cases, a two-second preparation step can improve overall reproducibility across an entire experiment.
Final Thoughts
Pre-wetting pipette tips is not a myth — but its importance depends on the context.
For high-precision work, small volumes, or viscous samples, it can significantly improve accuracy and consistency.
For routine transfers, its impact may be smaller but still beneficial.
Ultimately, good pipetting technique is about controlling variables.
And sometimes, one small step at the beginning can make the difference between stable data and unexpected variability.