Why Dry Ice Blasting in Winter Needs Dry Air

The Hidden Role of Humidity

Dry ice blasting depends on a clean, dry air supply. But in the UK, where humidity regularly swings from 60% in summer to over 90% in winter, moisture in the air can easily cause performance issues — even if your compressor already has an aftercooler and moisture separator.

When humid air is compressed, the water vapour it contains is squeezed into liquid form. An aftercooler removes most of this, and a moisture separator traps liquid droplets, but vapour always remains in the air. If that vapour cools again inside the blast hose or gun, it can condense and freeze, causing the air stream to pulse, the gun to block, or a white mist to form around the nozzle.

What’s Happening Inside the Air Line

Let’s look at what changes through the year:

As air cools downstream of the compressor — especially outdoors — any vapour near its dew point turns into water droplets. When that moisture meets sub-zero CO₂ in the blast stream, it freezes instantly. That’s why you might see ice forming inside the gun or a fog cloud in front of the nozzle.

Key Warning Signs

• Ice or water collecting in hoses or fittings

• Gun freezing or airflow pulsing

• Sudden pressure drops

• A “foggy” exhaust plume that lingers after each blast

How to Fix It

1. Install a dryer
   Add a refrigerant dryer (dew point around +3°C) or a desiccant dryer (down to –20°C or better). Either will stop vapour from reaching the blast hose.

2. Drain moisture traps daily
   Manual or automatic drains prevent liquid water building up in the separator.

3. Keep the compressor warm
   In winter, cover or shelter your compressor to reduce condensation in the lines.

4. Use insulated hoses
   Cold metal fittings act as condensation points — insulation helps keep vapour as vapour.

5. Blow off the system before each job
   Run air through the lines for 30–60 seconds to purge any residual moisture.

Quick Summary

High humidity is part of UK life — but in dry ice blasting, it’s your enemy.
A standard aftercooler and separator help, but when the air’s near saturation, you’ll need proper drying equipment to keep your air line frost-free and your blasting performance consistent all year round.

Need help choosing an air dryer?

CoolBlast can supply desiccant and refrigerant dryers to pair with your compressor setup.
Call 0330 127 2173 or email info@coolblast.co.uk for advice and options.