Nuke your Desiccant Packs

[Jim L]

Once desiccant packs reach their water storage capacity they no longer provide protection for your optics. Fortunately, many desiccant packs can be easily dried within a few minutes in the microwave.

Here’s a 50 gram (52 grams including the porous bag) pack that’s taken on 12 grams of water, or about 2.4 teaspoons worth; it’s full and no longer provides any further protection. The dark spots are beads that turn dark as they absorb water.

This pack is microwaveable and I put several into the microwave at a time, taking care to arrange them so that the released moisture has a way to escape. The small packs that came with the Takahashi didn’t change weight after microwaving which means they are not rechargeable and so I discarded them.

 

A few minutes later 12 grams of water have been removed and the rechargeable pack is ready to back into the case.

 

Here’s the case humidity before adding the desiccant pack:

 

The case internal humidity a few hours later that evening, and a very inhospitable environment for fungus:

 

The little hydrometer will let me know when the desiccant package needs drying, which is usually within one to three months depending on conditions and usage.

There are plug-in rechargeable desiccant packs but purchase them with caution. Many of them contain very little active ingredient in comparison to their weight, bulk, and cost, and can take hours to recharge; I don’t care for them.

Here’s the microwave rechargeable desiccant packs I use:

https://www.amazon.com/gp/product/B07TCGPZXK/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

They also have 112 gram microwave rechargeable packs which should last twice as long between recharges.

And here’s the little hydrometers I put in each of my cases:

https://www.amazon.com/dp/B08P3QJJZL?psc=1&ref=ppx_yo2ov_dt_b_product_details

Edited July 8, 2023 by Jim L

[Sunshine]

This is some great info, thanks!

[Franklin]

54% to 27% humidity is a great result and your test just goes to show how useful these little bags are. I've been using "Wisedry" for some time now with no complaints. I like the way they are supplied in airtight bags. 

[Jim L]

Here are the larger 112 gram microwaveable desiccant packs, which weight in at 114 grams dry. These will go into the four of my larger Pelican cases.

They cost just a bit over $4 per pack and recharge in under ten minutes. Based on the smaller packs they should remove up to about 60 grams of water, or five teaspoons worth, before they need recharging.

Here’s the source:

https://www.amazon.com/dp/B0876TS3RJ?psc=1&ref=ppx_yo2ov_dt_b_product_details

[Scott42]

Interesting, I didn't know you could use the microwave.  I've been baking them at 250 degrees F for 15 minutes, seems to get the job done.

I didn't think of weighing them to confirm the drying out - great idea.  Will try that next time. 

[Zermelo]

I saved dozens of the the little ones from COVID tests. I'd assumed that they would need a long bake in the oven, which I decided would be not worth the fuel. I'll definitely give this a go.

[Space Hopper]

Great topic Jim.

Thanks for sharing this info.

 

[Ratlet]

I picked up some large ones for putting in your car last year from Aldi.  They say to microwave for 6 minutes (!).  They work great.  I keep one under my oklop cover up the shed and another lives in my car where it does a great job of stopping the windows misting on cold mornings.

Need to get some more when the offer cycle gets back to them.

[Coco]

3 hours ago, Ratlet said:

I picked up some large ones for putting in your car last year from Aldi.  They say to microwave for 6 minutes (!).  They work great.  I keep one under my oklop cover up the shed and another lives in my car where it does a great job of stopping the windows misting on cold mornings.

Need to get some more when the offer cycle gets back to them.

Gotta love Aldi and Lidl..  Bought a band saw, pillar drill & stick welder amongst a myriad of other tools ...

[RT65CB-SWL]

On 08/07/2023 at 04:14, Jim L said:

Once desiccant packs reach their water storage capacity they no longer provide protection for your optics. Fortunately, many desiccant packs can be easily dried within a few minutes in the microwave...

What setting? 

The sachets I purchased were placed in the microwave [600w] on a paper plate as per the instructions... and the sachets split after two minutes. 

[Jim L]

1 hour ago, RT65CB-SWL said:

What setting? 

The sachets I purchased were placed in the microwave [600w] on a paper plate as per the instructions... and the sachets split after two minutes. 

I dry mine for 2 minutes at 700w, flip them around, and repeat for another two minutes. It’s the excitation of the trapped water that creates the heat so you want to be sure there’s plenty of air around the pack for the released moisture to escape. As the water is released, and there is less of it available, they don’t get as hot. One pack melted the plastic plate I placed it on, so they can get very hot.

My packs have a bag that is made of material much like Tyvek, which is very tough. The bigger danger to my packs is that the silica gel balls can fracture and that might not be good for them, but I keep within the products instructions and so far, other than the melted plate, everything has been fine.

It may be that all packs aren’t created equal, and some may not be as suitable for microwaving. The packs that shipped with my Takahashi scopes did not dry in the microwave, which suggests to me that they weren’t made for reuse. If the packs don’t claim to be microwaveable proceed with caution. In your case I’d use half the wattage and let them rest for a minute between heating.

 

[tomato]

Yes, several short sessions on low power is my approach to non microwave friendly desiccant packs, otherwise they get very hot and the pouches become sodden with the expelled water. Overall though, it can be quicker and use less energy than the oven.

But how about using an air fryer? They look like the ideal device for this purpose.

[bosun21]

2 hours ago, tomato said:

Yes, several short sessions on low power is my approach to non microwave friendly desiccant packs, otherwise they get very hot and the pouches become sodden with the expelled water. Overall though, it can be quicker and use less energy than the oven.

But how about using an air fryer? They look like the ideal device for this purpose.

Good idea 👍. Now where did i put that recipe book? On a serious note the dehydrate setting would be ideal for this 🤔.

[Naughty Neal]

I have a solar wax melter my try drying them out when the sun shines under the glass.

[Carbon Brush]

I looked at this a few years ago. Not all dessicant bags are created equal!

My first thought was recycling in a conventional oven.
This method is only financially viable if you are going to put lots of bags in the oven.

A microwave at first sight looks a good solution. It acts on the water so limits to 100C. So you think.
If the bag contents absorb microwave energy, you can have very high temperature in the bag.
In other words don't walk away. things can go bang or catch fire.
Maybe not on the spectactular level of placing ali foil trays in there, but you get the idea.
For example some crockery absorbs microwaves, others don't.
You see this when warming liquid and the container can remain cold, or can heat more than the liquid!

I did not have (one of these new fangled) air fryers at the time I looked. It sounds like a good idea.
A couple of litres of temperature controlled environment. On the list to try for the next drying session.

Some dessicants can absorb a lot of water, some very little.
The idea of a new dry weight marked on the bag is good.
But what is dry weight?

A new bag from the factory in a sealed poly bag can be assumed to be dry.
A useful looking bag removed from something shipped to you has of course been exposed to indeterminate moisture before delivery.

Then not all bags contain indicating pellets. When should I swap?

The final hurdle is that the adhesive to seal the bag, and the bag material may not be suited to high temperature.
Glue can melt and bag fibres break down.

So yes it can be done but it is not a 'one size fits all' solution.

HTH, David.

 

 

[Captain Scarlet]

I used to microwave one of the very big ones, sold as wet-shoe inserts, silica gel in a cotton bag. I put the microwave on to max, 800W, I forget for how long. But I then, for some idiot reason, decided to go for a run. While I was out my wife smelled smoke, went to the utility room to find a not-small fire in progress: the cotton bags had ignited. Boy was I in trouble!

So, as David mentioned one post up: “do not walk away”!

Magnus

Edited July 13, 2023 by Captain Scarlet