How Do Two-Way Humidity Packs Work for Cigars?
by Abraham Wolke
Before humidity packs, maintaining a humidor usually meant refilling a foam puck, watching a hygrometer, and trying to correct the humidity before it moved too far in either direction.
Two-way humidity packs made that much easier. Put the right number of packs in a cigar container with a good seal, close it, and check on it occasionally. When the air is too dry, the pack releases moisture. When the air gets too humid, it absorbs moisture. That is about as close to set-it-and-forget-it as passive cigar storage gets.
What does "two-way" humidity control mean?
A two-way humidity pack sits inside a closed humidor, storage bag, Tupperdor, or other cigar container. The formula inside creates a humidity level for the air to move toward. If the air outside the pack is drier than that target, water vapor moves out. If the air is more humid, the formula takes moisture back in.
At the target, the system is close to equilibrium. The pack is not reading each cigar or switching itself on and off. There is no pump, sensor, or open container of water. The formula and pouch do the work passively.
"Two-way" only describes the direction moisture can move. It does not tell you what ingredients create the target. Salt, glycerin, propylene glycol, and conditioned silica can all regulate moisture in both directions when they are used correctly. They do not all hold that target in the same way.
Why do we use salt-based formulas?
The FDA defines water activity as a measure of the vapor pressure over a material compared with the vapor pressure over pure water under the same conditions. In plain English, it tells us how readily the water in a formula can move into the surrounding air. Salt, glycerin, and propylene glycol can all lower water activity when dissolved in water.
A saturated salt formula contains dissolved salt along with extra salt crystals. When the pack releases water, some of the dissolved salt forms new crystals. When the pack absorbs water, some of the extra crystals dissolve. At the same temperature, that brings the liquid back toward the same balance of salt and water.
That is what "buffering" means here. The extra crystals resist changes in the formula's concentration. As water moves in or out, they help keep the pack's target RH from drifting with it.
Saturated salt solutions have long been used to create known humidity conditions for research and calibration. NIST's reference work on saturated salt solutions explains that excess solid salt lets a solution remain saturated even when it is exposed to modest moisture sources or sinks.
Glycerin-water and propylene-glycol-water formulas can also work in both directions, but their RH depends on the ratio of water to humectant. As the formula releases or absorbs water, that ratio changes and the RH drifts with it. A non-salt product may still work, but it does not have excess salt crystals continually bringing the formula back toward the same saturation point.
Conditioned silica beads work another way. Water adsorbs onto and desorbs from their porous surface. They can be reusable and effective, but they need to be conditioned to the desired level, used in sufficient quantity, and reconditioned as needed. The Canadian Conservation Institute's guide to silica gel gives a good technical explanation of that process.
Foam, cellulose cards, paper, and polymer gels are often just carriers. They hold a liquid and expose more surface area. The liquid or the way the carrier was conditioned usually determines the RH. A wet piece of foam filled with plain water does not become precise two-way humidity control simply because it can hold moisture.
That resistance to drift is why we use salt-based formulas. It gives us a stable foundation for precise passive humidity control at different RH levels. The finished pack still has to be mixed correctly, carry enough water, transmit vapor at the right rate, and hold up over time.
Does salt come out of a humidity pack?
No. During normal use, only water vapor passes through an intact Valet humidity pack. The liquid formula, salts, minerals, and other nonvolatile ingredients stay inside.
Valet uses a nonporous polymer film. Water vapor moves through that film at a molecular level while the bulk liquid and dissolved solids remain inside the intact pouch. Salt and minerals do not evaporate with the water, so they do not travel through the membrane and into your humidor.
We make Valet humidity packs with reverse-osmosis-filtered water and food-grade ingredients chosen to regulate RH consistently and remain compatible with the film and seals. Our design standard is simple: stable and harmless in normal use. If a pack is punctured, cut, torn open, or leaking, remove and replace it.
So no, a salt-based humidity pack is not putting salt on your cigars. The salt stays inside the pack and helps keep the RH stable.
How did salt-based humidity packs move cigar storage beyond 70/70?
For years, propylene-glycol solution was the standard way to regulate a wood humidor, and those systems tended to settle near 70% RH. That is where 70/70 came from. Your local tobacconist recommended it, cigar magazines repeated it, and the foam puck that came with your humidor was designed around it.
No scientific study had proved that every cigar was best at exactly 70% RH and 70°F. The available equipment landed near that range, it worked, and the standard stuck.
Salt-based humidity packs changed that because they could be formulated for a much broader range of precise RH targets. Instead of inheriting 70% from the humidifier, cigar smokers could choose 65%, 69%, 72%, or another level and see how their cigars responded.
Once people had that control, they began experimenting and many found that their cigars smoked better at a lower RH. Today, most of the serious smokers we hear from keep their cigars somewhere around 63% to 67% RH at home, especially when they enjoy heavier New World blends. We cover that shift in The State of Cigar Humidity Control in 2026.
That ability to choose the result created the modern state of cigar humidity control. It also removed most of the refilling and constant adjustment that came with older systems.
| Humidity system | How it works | What you have to manage |
|---|---|---|
| Plain water in foam or an open reservoir | Exposes water to the air and mainly adds moisture at cigar-storage RH | Refill it and watch the hygrometer closely |
| Propylene glycol or glycerin in foam, crystals, or another carrier | The liquid can absorb and release moisture; traditional propylene-glycol systems tended to sit near 70% RH | Maintain the liquid level and concentration as the target changes with the ratio |
| Conditioned silica beads | Adsorb and desorb water around the level at which they were conditioned | Use enough beads, monitor them, and recondition them |
| Salt-based two-way humidity packs | Use excess salt crystals to resist concentration changes and target different RH levels | Size them correctly and replace them when depleted |
| Electronic humidifiers | Use a sensor, fan, and water reservoir to add moisture when RH falls below the setting | Supply power, refill the reservoir, calibrate the sensor, and maintain the unit |
Electronic humidifiers can be the right choice for a large cabinet, retail display, or walk-in humidor. Most common cigar units add moisture when the sensor reads low and stop when they reach the setting. They generally do not pull excess moisture back out of the air, so they are active humidifiers rather than passive two-way humidity control.
For desktop humidors, bags, plastic containers, and cooler storage, a ready-to-use humidity pack asks much less of the owner. There is a recurring replacement cost, but there is no reservoir to fill, no power cord, and very little day-to-day adjustment.
What does the number on a humidity pack mean?
The number printed on a humidity pack is its rated RH. In a properly sealed container, with enough humidity packs for the container's capacity and a stable temperature, the air should settle near that number.
The printed number is not necessarily the final reading you are aiming for. Your container is part of the system. A tightly sealed plastic container will usually stay closer to the pack's rating. A wood humidor or another more breathable container may settle a few points lower because it loses more moisture. If you know your humidor runs a few points below the pack rating, you may intentionally choose a 69% or 72% pack to get the RH you actually want inside the container.
So the right question is not just, "What RH do I want?" It is, "Which pack rating will give me that result in this container?"
The seal, dry wood, cigar load, number and condition of the packs, how often you open the container, temperature, sensor placement, calibration, and time can all change the reading. A hygrometer that sits one or two points away from the number on the pack is not automatically showing a problem.
Temperature matters too. Relative humidity is temperature-dependent, and every passive system, including a saturated salt formula, can shift as temperature changes. Store cigars in a reasonably cool place and avoid large, fast temperature swings whenever you can.
The air also changes before the tobacco does. Your hygrometer measures the air near the sensor, not the moisture at the center of every cigar. Give the cigars time to adjust before deciding a new RH is not working.
If you are choosing a pack for a wood humidor, our guide to 69% versus 72% humidity packs explains how to find a starting point without relying on a fixed wood offset.
A humidity pack also changes what the container has to do
Once the humidity pack provides the moisture buffer, the container has a much simpler job. It needs to seal, protect the cigars, and give you enough room to organize them.
That has made plastic the go-to storage option for many serious collectors who are in it for the cigars. Plastic is not performative. It just works.
A humidor bag is a resealable bag made for cigar storage. A Tupperdor is an airtight food-storage container used as a humidor. A clean insulated cooler can also become a large cigar-storage container. It does not refrigerate the cigars, but its insulation slows outside temperature changes, which can help keep the conditions inside from swinging as quickly.
Wood humidors are still beautiful. They can be a great display piece as your collection grows. We just do not think a new smoker needs to spend heavily on equipment before spending money on cigars.
If you add a cedar tray, shelf, or box to plastic storage, remember that the wood can still absorb moisture. Dry cedar should be seasoned before you ask a maintenance pack to humidify the cigars. Our full Tupperdor versus wood humidor guide covers the tradeoffs in more detail.
Shipping cigars and storing them at home are different jobs
A cigar maker or retailer may use a 69% or 72% humidity pack when shipping a box, even if the recipient prefers a lower RH at home. The extra moisture can help the wrappers stay pliable as the box moves through changing climates and gets handled in transit.
That does not mean the sender chose the wrong RH, and it does not mean you need to store the cigars at that level forever. Shipping is about helping cigars arrive intact. Home storage is about how you want them to age and smoke. After delivery, give the cigars time to acclimate, then move them to your normal storage setup.
What can a two-way humidity pack not do?
A humidity pack makes storage easier, but it cannot fix every part of the system. It does not control temperature or compensate forever for a bad seal. Dry cedar still needs to be seasoned, and a packed cabinet may not have identical conditions in every corner. A humidity pack also cannot recover a dry cigar overnight, make mold impossible, or keep working after its water reserve is gone.
A pack that dries out unusually quickly is often telling you something useful. The container may leak, the wood may be dry, the cigar load may be unusually thirsty, or you may not have enough packs for the container's full capacity.
Check the pack, the seal, the wood, and the hygrometer before assuming the chemistry failed. A depleted Valet pack feels stiff and crystalline, although it may not be completely brittle.
How do you use a humidity pack?
- Start with a clean container that has a reliable seal. A humidity pack lasts longer and works more predictably when it is not constantly conditioning outside air.
- Choose one RH level based on the container and how you like your cigars to smoke. Do not mix different RH ratings because the packs will work against one another.
- Size for the container's full capacity. Our guidance is one Valet 60g pack for every 25 cigars the container is designed to hold, even if it is not full today.
- Season any dry cedar first. Otherwise, the wood can absorb the moisture that should be helping the cigars.
- Close the container and give it time. The air may begin changing quickly, but the full setup takes longer to settle and the cigars can take weeks to equilibrate.
- Check the packs occasionally. Replace a Valet pack when it feels stiff and crystalline, although it may not be completely brittle.
You can use The System to match the pack to your container, desired result, and capacity.
A few common questions about humidity packs
How long does a humidity pack take to work?
The air inside a closed container can begin moving toward the target fairly quickly, but do not judge a new setup after a few hours. Give the container several days to settle. If you are trying to change the condition of the cigars themselves, think in weeks rather than hours.
Can I use a humidity pack in a storage bag?
Yes. A purpose-built humidor bag or clean freezer-grade storage bag can work for travel or temporary storage if it seals reliably. The bag still needs to protect the cigars from being crushed, and thin or damaged bags will exchange more air.
Do I still need a hygrometer?
You do not need to stare at one all day. A correctly sized humidity pack in a simple airtight container should handle routine moisture control. A calibrated hygrometer is still useful for catching a leak, dry wood, a depleted pack, or a temperature problem.
Can I mix different RH levels?
No. A 65% pack and a 72% pack in the same container will work against each other. Choose one target for each container.
Why are so many cigar smokers using two-way humidity packs?
Other humidity systems can work. For many cigar smokers, two-way humidity packs have become the go-to for personal storage because they are simple, portable, and easy to scale. The right number of salt-based humidity packs in a sealed container gives you a stable target without turning cigar storage into a second hobby.
Start with a bag or Tupperdor if that is what makes sense, and spend the money on cigars. Buy the wood humidor when you want it as part of the room, not because somebody told you it was the price of entry.
At Valet, we want humidity control to be easy to understand and easy to choose, and we plan to keep improving it. If you know your container and the result you want, shop all Valet humidity packs or use The System to find the right one.