Soaks in Detection Dog Training: Uses, Risks, Contamination and Best Practice

Soaks have become a common tool in detection dog training. A cotton pad, a piece of gauze, a fabric swatch, sometimes a wooden cocktail stick — often associated with liquid scent or target odour solution — and suddenly you have a “training aid”. Convenient. Cheap. Easy to deploy. Essentially, you can use almost anything as a soak item. 

But it’s important to clear up a common misunderstanding straight away:

A soak does not have to be soaked in a liquid at all.

A soak can simply be:

• Placed in the same jar as the target odour
• Allowed to absorb vapour only
• Either touching the target material briefly
• Or kept completely separate using a divider inside the same container

My preferred choice for storing odour is glass jars. Some of the glass jars I use are fitted with glass dividers, which allows the target odour to remain physically separate from the soak item while still sharing the same odour environment. That gives far greater control over:

• Odour transfer
• Strength
• And contamination risk

It’s also important to clarify how controlled drug samples are managed. When I am working with substances such as cocaine, the sample itself is kept inside a small sealed bag which is never opened. Each of these bags carries its own serial number, allowing full traceability and accountability.

The target substance stays sealed at all times.

Only the vapour is allowed to permeate the surrounding container and any authorised carrier (such as filter paper or a controlled soak item). This ensures:

• The integrity of the substance
• Legal compliance
• No direct handling of controlled drugs
• And far greater contamination control

When I store my soak items alongside controlled drug samples, the process is straightforward and fully controlled. The drug samples remain sealed inside their own individual bags at all times, and I simply place the soak items directly into the same glass jar. This means the soak items sit in full contact with the exterior of the sealed bags, allowing vapour transfer, but never direct contact with the drug substance itself.

This maintains:

• Odour integrity
• Legal compliance
• Zero direct handling of controlled drugs
• And consistent, controllable vapour exposure for the soak items

So yes — liquid soaks exist.

But vapour-only soaks exist too, and the two behave very differently in training.

Convenient? Yes.

Simple? Yes.

But also one of the most misunderstood and misused tools in modern detection dog training.

Used correctly, soaks can have a place.

Used badly, they quietly damage odour recognition, contamination control, and ultimately operational credibility.

This blog isn’t about banning soaks.

It’s about telling the truth about them.

Soaks: Useful Tool or Hidden Problem?

Let me be absolutely clear from the outset:

I would never use a soak item to imprint a dog on odour — whether that dog is completely green or already experienced.

Soaks should never be used for the imprinting process. Ever. This is my opinion.

Imprinting is the foundation of the entire detection picture. It is where the dog learns what the odour is, not just that some vague scent leads to reward. That foundation must be built on real target material, not a liquid simulation carried on cotton, paper, or metal.

That said, soaks are not automatically “bad”. Like most things in detection dog training, they can be useful or damaging depending on how they are used.

Over the years, I’ve used a wide range of carriers for soaks, including:

• Cotton wool
• Q-tips
• Small metal filter discs
• Whatman filter paper

Each of these behaves differently in terms of:

• Odour release
• Retention
• Transfer
• And contamination risk

That alone should tell you something important — not all soaks are equal, and they certainly shouldn’t be treated as interchangeable.

Used correctly, soaks can:

• Support controlled discrimination exercises
• Assist with limited odour exposure once a dog already understands real target
• Help in restricted environments where real material is temporarily unavailable

Used badly, they can:

• Flood training areas with uncontrolled odour
• Contaminate boxes, vehicles, rooms, and equipment
• Teach dogs that target odour is always easy to access
• Create wide, sloppy search behaviour
• Inflate false indications
• And quietly undermine operational credibility

Soaks are not the problem.

How they are managed is the problem.

What a Soak Actually Is (and Isn’t)

A soak is not target material.

It is:

• A carrier (fabric, cotton, paper, metal)
• Impregnated with a liquid solution or exposed to vapour
• Designed to simulate part of an odour profile

That immediately makes it:

• More volatile
• More transferable
• More prone to contamination
• Easier to leak into the environment

Which means the dog is not learning “find the substance” — it is learning to locate a highly mobile odour footprint that behaves very differently to real-world concealments.

The Contamination Problem No One Wants to Talk About

Soaks are one of the biggest contamination accelerators in training:

• They leak into boxes, vehicles, rooms, bags, walls
• They transfer onto hands, leads, towels, floors
• They sit in kit bags next to blanks
• They are reused again and again without true control

Before long:

• Every box smells
• Every vehicle has background target odour
• Every training venue is “dirty”
• And every blank becomes questionable

The dog doesn’t get confused.

The dog adapts.

It widens its criteria.

And that’s where false indications are born.

Leaving Soaks Behind Is Another Hidden Training Error

Another mistake I see far too often is the belief that because a soak has been contaminated with cocaine vapour, Semtex vapour, or even something as simple as clove in nose work, it’s somehow acceptable to leave those soaks out at the end of a training day.

It isn’t.

Every contaminated soak left behind becomes:

• A background odour source
• A silent contamination point
• And a future false decision waiting to happen

I see this regularly not just in operational training environments, but also in nose work groups, where clove-contaminated soaks are left sitting around in training venues, bags, or open rooms. That should never happen. It is poor practice, full stop.

If you wouldn’t leave real target material lying around, you shouldn’t be leaving soak-contaminated carriers lying around either.

Failing to collect and control soak items at the end of training:

• Pollutes future sessions
• Weakens blank integrity
• Creates drifting background odour
• And quietly sabotages the dog’s decision-making

Good training doesn’t end when the last hide is found.

It ends when every contaminated item is accounted for and secured.

The Soak Item Itself Becomes the Problem

One of the most common mistakes I see with soak use is that handlers fail to teach their dogs to ignore the soak carrier itself.

If a handler uses Whatman filter paper as a soak carrier for cocaine vapour, then the dog should also be exposed—regularly and deliberately—to blank, unsoaked Whatman filter paper in training.

Because what we do not want is for dogs to become imprinted on the soak item itself — and this can very easily happen if blank, unsoaked versions of that same carrier are never used in training.

If this step is skipped, the dog can begin to associate:

• The paper
• The texture
• The handling residue
• Or the carrier material itself

instead of the target odour.

At that point, the dog is no longer purely odour-driven — it is partially object-pattern driven. That’s when:

• False indications start to creep in
• “Paper-only” finds appear
• And handlers wrongly blame the dog instead of the training design

This applies to all soak carriers:

• Cotton wool
• Q-tips
• Metal filter discs

If a dog is trained on a carrier, it must also be trained to ignore that same carrier when it is blank. There is no shortcut around this.

If your dog can’t confidently ignore a clean, dry, odour-free version of your soak item — you don’t have odour clarity. You have pattern learning.

Soaks vs Real-World Odour

Real illicit material behaves very differently to a soak:

• It is often sealed
• Wrapped
• Boxed
• Bagged
• Buried inside layers of concealment
• Sitting cold, stable, and inaccessible

A soak:

• Bleeds odour freely
• Creates massive vapour cones
• Teaches the dog that target odour is easy to access

Then handlers are shocked when:

• The dog struggles in real vehicles
• Shows uncertainty in apartments
• Gives changes of behaviour but no final response
• Or works wide and messy

That’s not weak detection.

That’s honest detection colliding with unrealistic training.

When Soaks Were the Right Tool – The Whisky Dog Project

When I trained the world’s first whisky detection dogs, soak items played a major role in the later stages of training — but only after the dogs were correctly imprinted on the real target odour itself.

The dogs were first imprinted on 5 grams of real target material. That part was non-negotiable. I wanted the dogs to learn the true odour profile at source, not a simulation.

Once that understanding was fully in place, I then systematically reduced the training quantity:

• From 5 grams
• Down to 0.5 grams

My operational requirement was that the dogs needed to be capable of locating the target odour down at 3 parts per trillion (3 ppt). That meant they had to work at extreme trace levels, not just bulk finds.

Only after the reduced-quantity foundation was fully established did I begin to introduce soak items.

I started with Whatman filter paper that had been exposed to whisky vapour for two weeks, and then worked progressively down through shorter exposure times — right down to Whatman filter paper discs exposed for just one hour.

That wasn’t random.

It was a deliberate attempt to replicate in training the same part-per-trillion vapour picture the dogs would be required to locate operationally.

And this part is critical:

My soak items never came into direct contact with the target odour. Ever.

They were exposed only via vapour transfer, not physical contact. This was done deliberately to:

• Prevent contamination
• Prevent cross-contamination
• Maintain odour integrity
• And stop uncontrolled background odour from developing in the training environment

This progression:

Bulk target → reduced grams → extended vapour soak → short vapour soak → trace-level searches

is exactly how soaks became a controlled scientific tool, not a shortcut.

One of the most rewarding things to witness in detection dog training — especially when working with soaks — came during the final stages of trace-odour development. At this point I was using a small metal filter disc that had been exposed to the target odour for just five minutes. The disc sat inside a sealed jar, separated from the source by a glass divide, so the only transfer happening was vapour, not physical contact.

In a lineup of five identical consoles, the dogs consistently identified the correct target console containing the briefly exposed metal disc — and just as importantly, they ignored the blank metal disc placed in the same lineup. No change of behaviour, no interest, nothing.

For me, this was remarkable to witness. It showed, in real time, that a dog can differentiate between:

·       a metal disc with five minutes of vapour exposure

and

·       an identical metal disc with zero exposure

This level of discrimination proved that the dogs weren’t guessing, weren’t following handler influence, and weren’t responding to anything except the true target odour signature, even at an exposure time so small most humans would assume it’s meaningless.

It was the perfect demonstration of why controlled soaks — used correctly, in the right sequence, after proper imprinting — can reveal a dog’s true ability to work at trace levels, not just bulk odour.

Why Soaks Were Essential in Early UK TATP Training

During the first few years that explosive detection dogs were being trained on TATP here in the UK, soak items were used extensively — out of necessity, not convenience.

TATP was, and still remains, one of the most volatile and dangerous materials to work with in explosive dog training. Direct handling and repeated exposure simply weren’t practical or safe. So instead, controlled soak items were used to allow training to take place while managing very real safety risks.

In this case, the soak item was typically a small Whatman filter disc, sealed inside its own individual bag.

I vividly remember being told by a scientist that once that filter disc was removed from its sealed bag, we only had around 20 minutes to train with it before the odour had effectively vanished.

That single statement says everything about:

• How volatile the odour picture was
• How transient the vapour actually is
• And how time-critical soak-based training can be

Soaks may look strong at first, but their odour picture can collapse far faster than most handlers realise.

Odour Decay with Soaks – What Handlers Often Forget

One of the biggest misunderstandings with soak use is the belief that a contaminated soak stays “good” indefinitely. It doesn’t.

Soaks suffer from odour decay — often far faster than people realise.

Once a soak item is:

• Removed from its sealed storage
• Exposed to open air
• Handled repeatedly
• Or left sitting in a training environment

the vapour concentration starts to collapse almost immediately.

Depending on:

• The volatility of the target odour
• The material of the carrier
• The temperature
• The airflow
• And the surface area

a soak can go from strong → weak → functionally blank in a surprisingly short period of time.

This was made very clear to me during early UK TATP training, when I was told that once a sealed Whatman filter disc was removed from its bag, we had roughly 20 minutes of usable odour before it had effectively decayed beyond reliable use.

That single fact destroys a lot of lazy soak practice.

If handlers are:

• Reusing old soaks
• Leaving soaks out for hours
• Carrying soaks loose in pockets or kit
• Or assuming yesterday’s soak is still valid today

then they are very likely training on decayed vapour, not true target odour.

At that point:

• The dog isn’t wrong
• The odour picture is

And that’s how uncertainty, weak indications, and false negatives quietly creep into a system.

Soaks do not just contaminate.

They also fade — and both ends of that problem must be managed.

When Soaks Were Used as a Welfare Tool – Broadmoor Hospital

When I worked at Broadmoor Hospital, the work was physically and mentally hard for the dogs.

On many days, dogs were expected to search in excess of 40 rooms per day — both tobacco dogs and drugs dogs — across:

• Patient bedrooms
• Kitchens
• Corridors
• Communal showers
• Day rooms
• Offices
• And visiting areas

Security was understandably extreme. Access for me and the dogs involved a tight, time-consuming security process, and I couldn’t simply come and go as I pleased. Every movement was controlled.

The dogs also worked long hours, and on some days they could search for hours without finding anything at all.

From a welfare and motivational perspective, that mattered.

On those long, uneventful days, I wanted to give the dogs a “sweetener” — a morale booster that maintained:

• Motivation
• Drive
• Engagement
• And reward expectation

But I couldn’t be walking into Broadmoor with a Peli case full of real drugs. That simply wasn’t realistic or appropriate in that environment.

So in that specific operational context, soaks were something I relied on heavily — not for imprinting, not for shortcuts, not for replacing real odour — but simply as a controlled way to give the dogs a legitimate reward outcome during long, demanding, sometimes empty days of searching.

Here, soaks served a welfare function, not a training crutch.

And that distinction matters.

You Don’t Need “Specialist” Hardware to Create a Soak

There’s a growing trend in detection dog training towards expensive, purpose-built vapour carriers that are marketed as “professionally manufactured soak systems.”

Let me be clear about something important:

You do not need proprietary, high-cost equipment to create a soak item.

A soak is still just:

• A carrier
• Holding vapour
• From a target odour

That’s it.

We’ve been doing that for decades using:

• Cotton
• Paper
• Fabric
• Filter discs
• Metal carriers
• And controlled vapour jars

The idea that a soak suddenly becomes more “professional” because it comes with a hefty price tag is marketing — not science.

If your:

• Imprinting is correct
• Contamination control is strict
• Blanks are properly trained
• Odour decay is understood
• And training design is sound

then a simple, controlled carrier will perform exactly the same function as any expensive manufactured soak product.

What matters is:

• How you expose it
• How you store it
• How long you use it
• How you control it
• And how you proof against it

Not what logo is printed on the packaging.

In fact, the real danger with expensive, specialist vapour products is that people begin to treat them as:

• Shortcuts
• Replacements for real target material
• Or validation that their training system is “advanced”

Price does not equal credibility.

Design does.

If a system needs costly hardware to appear effective, that’s usually masking a flaw elsewhere in the process.

So yes — modern vapour carriers exist.

But we don’t need to be sold them as something mystical or essential.

At the end of the day:

A soak is still just a soak.

And all the same rules still apply.

The Training Shortcut Trap

Soaks are often used because:

• Target material is hard to get
• Storage is awkward
• Licensing is limited
• Accountability is uncomfortable

So instead of solving the real logistical problems of proper target management, some programmes replace substance control with scent illusion.

It looks productive.

It feels busy.

It ticks boxes.

It fills courses.

But it quietly strips credibility from the system.

Final Thoughts

Soaks are not good.

Soaks are not bad.

Soaks are a tool — and like any tool, they only work as well as the system that controls them.

Used with:

• Real target imprinting
• Strict contamination control
• Proper blank exposure
• Time-aware odour decay management
• And clear operational purpose

they can become precision instruments for trace-level work.

Used casually, lazily, or as a shortcut, they don’t just weaken training — they reshape what the dog believes the job actually is.

Dogs don’t misunderstand soaks.

They simply learn exactly what we show them.

If training with soaks ever becomes easier than training with real material, that’s a warning sign — not a success.

Because in the real world:

• Odour is sealed
• Access is restricted
• Vapour is weak
• And the environment is never tidy

Soaks should prepare dogs for that difficulty — not protect them from it.

That’s the difference between:

• Dogs that look good in training
• And dogs that perform when it actually matters.