How much desiccant do you need to protect your goods from moisture damage?

When you’re looking to protect your goods from moisture damage, working out how much desiccant you need is a tricky business. Mostly because there are no short cuts and no simple formula where you input a few numbers and then get a definitive answer. There are just too many variables. Plus, theoretical performance rarely matches real-life conditions and outcomes, so it can only point you in a very rough direction. Which is no good if you really want to make sure your precious cargo is fully protected – while also making sure you’re not wasting too much time and money on over-dimensioning just to be on the safe side.

We’re going to delve into the complexity and difficulty here. Not to overwhelm you or make you lose all hope, but ultimately to show you that there’s a clear, simple and better way forward. So sit back and relax as we take you on a tour of all the things you will no longer need to worry about.

No two shipments are the same

Let’s start with the different questions and factors that affect any calculation of how much desiccant you’ll need:

• What is the cargo and does it release moisture or not?
• How is it packaged?
• What is the moisture content of the packaging material e.g. pallets and boxes?
• How big is the container and what is the air volume when it’s loaded?
• What is the quality of the shipping container? Is the floor dry and are the vents sealed?
• Where is the container on the vessel? Above or below deck? Inside the stack or fully exposed?
• How long will the goods be in transit? And do you need to add waiting time at either end?
• Where is the cargo coming from and going to? What are the weather conditions at loading and on the shipping route?

So, lots to address there. And clearly one size does not fit all – almost every shipment will be different, and the variables and resulting desiccant solution can change with it.

Theory vs. Practice

But if that wasn’t complicated enough, you’d then need to factor in how different desiccants actually perform in real life. Because the performance metrics almost always relate to climate chamber tests that bear little resemblance to shipments in the real world.

The climate chamber tests usually show how desiccants perform in near-perfect conditions with high relative humidity and high temperatures that are kept constant throughout the test, unlike the completely different highs and lows of days and nights at sea. So sometimes the maximum effectiveness is only reached at a constant 30 °C and 90% RH – and at the end of a test that is twice as long as the usual shipment time of 3-4 weeks.

That’s like quoting the fuel consumption of a car when it’s only tested going down a steep hill – and with a hurricane-strength wind behind too!

So you need to be wary of the numbers suppliers give you, especially with absorption capacity figures as high as 300% or more, which are probably at least half that in the real world. Certainly, if you take them at face value and think you’re protecting your container with say 2.5 kg of desiccant when it turns out you actually needed 5 kg.

Finding some peace of mind

Luckily for everyone, we’ve collected our own real-life performance data over many years and many different voyages – charting the performance of our own 94% calcium chloride desiccants as well as our competitors’ products and alternatives like silica gel and clay. That’s all about being truly confident that the proposed solution really does its job protecting your cargo against moisture damage – and as cost-effectively and sustainably as possible too.

Remember that “clear, simple and better way forward” we promised at the top? You’ll be pleased to hear that this is where it starts to emerge. We have put all of our moisture knowledge, desiccant performance data and real-life container insights into our approach for building solutions that are tailor-made for our customers, their cargos and the conditions they are dealing with. Appropriately, it’s called Peace of Moisture Mind® (POMM) – and Step 2 of 4 is even dedicated to dimensioning the solution and making sure all the critical cargo, packaging, container and transit variables are factored in.

The way forward?

Put simply, we’ve learnt everything we can about desiccant performance and optimal moisture damage prevention so you don’t have to. Read more about POMM moisture damage prevention here. And contact your local Absortech representative about starting the full process – or even just Dimensioning as a stand-alone step.