At the end of the day, I'm attempting to find a "happy medium" dehumidified storage solution between ElCheapo high maintenance/poor space efficiency and an industrial/commercial zero maintenance but expensive pre-made cabinet for an
actively used dry box/cabinet. Using cheap materials with a lower end commercial dehumidifier or vice versa is within range. The 2 biggest reasons I'm trying to DIY a custom build is that my previous solution worked well enough for long term storage, but every time I opened the box to add a new roll or get one out for use, it would start from scratch and take a couple weeks to reduce humidity again (plus have to swap out the desiccant each time). As pointed out, a fan would help speed up the process, but the dehumidifying problem is the same. The second big reason I'm doing a custom build is because my office/workshop/lab/printshop/and general storage room is cramped for space, especially space useful for something other than storage. For instance, I can't mount spools underneath my printer because I have a pile of lumber there.
Rebuilding my previous containers to be able to mount spools for active use (spools can spin and filament is tubed out the side to printer with PTFE) waste a significant amount of space due to off-the-shelf container dimensions. The dry box I'm attempting to build will mount on the wall between my workspace and the above up-to-the-ceiling shelves, and has enough room for 40+ filament spools, each mounted and ready to use with a shared dehumidifying solution. Compared to a max of about 10 spools with a minor upgrade to my previous solution with 2 separate dehumidifiers and using up valuable workspace since there is no good way to mount the containers on the wall.
But "why" build a custom dry box is probably obvious to you, so I'll stop my rampagy digression.
@ Everyone who's posted: Thanks for the pointers and links! I've attempted to condense the info below.
@ Kleinstein: Thanks for pointing out the issue of choosing materials for cabinet walls and sealants. I guess that means this topic is really 2 questions: dehumidifying and appropriate material options. Generally speaking, I have no idea what specific materials are good for humidity isolation, and what is more of a "screen door" for water vapor.
Materials Choice for Walls:Best but potentially more difficult to work with: Metal, glass (acrylic?)
Cheaper and potentially easier to work with: Plastic sheeting (but which type is ideal for $/humidity isolation?). I've considered the following so far:
- Plastic sheeting intended for weather proofing windows, for example: $30/roll
https://www.amazon.com/Warp-Bros-NFG-36P-Flex-O-Glass/dp/B001457JBS/- 12 Gauge clear PVC sheet, similar material as heavy duty shower curtain (or literally cut up an $11 shower curtain):
https://www.amazon.com/gp/product/B07YFPPH4Q/Materials Choice for Door Seals (and/or gaps in walls for filament/PTFE):It's probably best to seal individual PTFE tubes where they go through the wall with caulking/sealant, but using a long narrow gap in the wall to snake out PTFE tubes between weather stripping (if it'll maintain a good enough seal) is a much more flexible solution and allows variable "where and how many" filaments are externally accessible without opening the dry cabinet. I've considered the following so far:
- self adhesive magnetic tape (door or "plastic flap door" only):
https://www.amazon.com/Magnetic-Adhesive-Backing-whiteboards-Organization/dp/B07QKNZZ3J/- open cell foam weather stripping similar to neoprene, no idea how much the material "breathes":
https://www.amazon.com/gp/product/B0814KHG9T/- closed cell vinyl foam weather stripping, no idea much about it, but it was $2 for about 3 meters of material:
https://www.amazon.com/gp/product/B01NAH18WF/Materials Choice for Sealing wall material seams, edges, small gaps, etc:- Silicone Caulking, but some varieties are in the "screen door for humidity" category of materials
- ? I want to say some type of epoxy, but that seems overkill, and a bit of a PIA for a larger project. I would think something suitable would be available for a caulking gun, but no idea what to look for since "water seal" and "humidity seal" are 2 different things.
Dehumidifier, Condensing Compressor Type: Minimum RH% achievable at room temperature = *?*Pro's: Removes moisture significantly faster than other methods and can be more power efficient
Con's: Much noisier than other solutions and typical consumer-grade units are large and bulky, too big for small to medium sized dry cabinets.
Options: I'm not sure if smaller or more compact units are even manufactured... ? I have a floor standing unit in the other room that can drop humidity from 65% to less than 40% in a few hours for several decent sized rooms. In a sealed area (without an external door opening/closing throughout the day), it should be able to hit 35% without too much additional time. If it were smaller with lower volume/minute fans, I'd just duct tape a hose to it, throw it into my cabinet and call it a day, but waaaay too big for that.
Options:
- To-Be-Discovered compact commercial/industrial compressor type unit, if such a product exists
- (I THINK this is a compressor type...):
https://www.aliexpress.com/item/33008690071.html?spm=a2g0o.productlist.0.0.3a031c1bdFxSqs&algo_pvid=5aad1fb7-1a86-46f1-8ede-2e7bd6013eb8&algo_expid=5aad1fb7-1a86-46f1-8ede-2e7bd6013eb8-2&btsid=0ab6f82c15818565280654285eceb7&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_Dehumidifier, Condensing Thermoelectric/Peltier Type: Minimum RH% achievable at room temperature = *?*Pros: Quiet, very compact units are commonly available.
Cons: Removes moisture much slower that compressors, at least for common consumer grade products. Not sure about commercial/industrial units.
Options:
- Commercial grade unit:
http://www.amstechnologies.com/products/thermal-management/thermoelectric-technologies/thermoelectric-cabinet-coolers-and-dehumidifier/view/thermoelectric-dehumidifier-device/Dehumidifier, "Humidity Trapping" Type: Minimum RH% achievable at room temperature = *?*Pros: Cheap, renewable, commonly available, likely the optimal and ideal solution for long term storage when the container remains
constantly sealed.
No idea if silica gel/molecular sieves can achieve better (or worse) RH% than condensation type dehumidifiers.Cons: Very very slow to absorb humidity (can be sped up a little with fan), so not ideal for a dry box that gets opened up at any regular interval or has even a small flaw/gap in construction. Renewing desiccant usually requires opening the dry box, compared to compressor/thermoelectric that you just flip a switch from outside the cabinet.
Options:
Cheap silica gel, but per good advice, molecular sieves of grade 3A, 4A or 5A are a better choice.
Dehumidifier, "Other?"As I was digging around, I found some type of "mechanical" molecular sieve that is apparently used in refrigeration units... I have no idea what it does or if something similar might be usable for dry cabinet purposes, so thought I would temporarily include it on the list until someone corrects my ignorance:
https://www.amazon.com/Danfoss-Liquid-Drier-Sweat-Connection/dp/B06XXTCRQ7/Other thoughts or suggestions? If I have something wrong, please correct me. If you've had similar issues when building your own dry box, I'd love to hear how you dealt with them.