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Tropics: How to protect optics from very high humidity

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#1 TonyInHonduras

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Posted 11 February 2024 - 06:59 PM

I live in Central America with very high humidity at certain times of year. Any suggestions on how to protect optics s like a short focus refractor and eyepieces? I've already lost much equipment to this scourge... Thanks!



#2 TOMDEY

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Posted 11 February 2024 - 09:20 PM

Gun safe heater --- that's what I used in the jungles of Panama and it worked fine for the year and a half I was there (researching insect vision). You run it all the time in your storage locker. Draws only a few watts (comes in different sizes) and it completely prevents condensation and mildew.       Tom

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#3 Keith Rivich

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Posted 11 February 2024 - 11:31 PM

I live in Central America with very high humidity at certain times of year. Any suggestions on how to protect optics s like a short focus refractor and eyepieces? I've already lost much equipment to this scourge... Thanks!

On a similar note to Tom I use gun safe desiccant packs to keep my optics nice and dry here in the very humid SE Texas. Works just fine. 



#4 maroubra_boy

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Posted 12 February 2024 - 11:11 PM

If you have desiccant packs in a gun safe, then the house will also be air conditioned, which really renders the desiccant irrelevant.

 

Desiccant should only be used as a stop gap measure once the scope is PROPERLY dry both outside AND inside.  It should be the last line of defence against damp, NOT the first.

 

The actual amount of water that desiccant packs can absorb is actually very small, which is why they should not be relied upon to dry anything and only be a last line measure.  Once the desiccant is saturated, which will happen quickly in a humid environment it is totally useless.  As a result they will need regular changing and recharging - something that loses is appeal very quickly after a couple of weeks.

 

Humidity a big problem, as well as stagnant air.  I have seen beautiful and expensive scopes ruined because they were not kept in a dry environment.  In one instance a brilliant 7" Mak which was kept in its original metal box AND with a desiccant pack, was totally ruined, scope, case and all by mould.  It was kept in a garage that had no ventilation and as with most garages, was not damp proof and not air conditioned.

 

High humidity is also a BIG problem for us here in Sydney.  My man-cave is a converted stand-alone garage which developed a damp problem soon after being converted.  This is also where I keep my astro gear and all my tools.  I struggled with keeping rust off my tools and lived in fear of how my astro gear was doing.  I spent a goodly amount of money on desiccant and made many packs to stuff into focusers and cases, but the desiccant lasted for only a few days before it was saturated and ineffective.

 

The single best purchase I have made for EVERYTHING in my man-cave was installing a de-humidifier.  I have its drainage hose bleed into the drain of the sink in the man-cave.  In just the first 24 hours that I had the dehumidifier running the air inside the man-cave totally changed.  The unit I have is a small one, enough for a room, low power consumption and it does an outstanding job.  I also have a small fan running in the man-cave to make sure air does circulate effectively through the room.  I no longer use any desiccant packs at all.

 

After an astro session in my backyard my gear is routinely soaked with dew.  I bring all my gear into the man-cave and leave it all open in the room and leave it to have the de-humidifier dry it out.  This is more important than you think as dew will be wicked into all manner of nooks and crannies of your scope, gear and mounts.  If you think your gear is dry because you no longer see any water on the surface, you are sorely mistaken.  It is this hiding and trapped water that accumulates over time and causes damp and mould problems.  Leaving all the gear, scopes, eyepieces, cases, EVERYTHING open for the dehumidifier to dry it out overnight draws out ALL the water, outside and inside of the kit.  Only then do I pack away everything.

 

Air conditioning does the same job as a dehumidifier, but installing an air-conditioner just for your astro gear needs careful consideration as it is power-hungry.  A dehumidifier uses a fraction of the power in comparison.  But an air-conditioner is also not a bad idea to help keep your gear cool during the day in preparation for an evening session, reducing both the cooling period (if any) and preventing thermal issues from say inside a personal obs.  Isolation and insulation of such a structure is also of major benefit for the effectiveness of this.  Remember, professional observatories are also giant cool rooms that are air conditioned so that these big instruments and structures don't become warm during the day - there won't be enough hours in a night for such instruments too sufficiently cool otherwise.

 

Alex.


Edited by maroubra_boy, 12 February 2024 - 11:12 PM.

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#5 TOMDEY

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Posted 13 February 2024 - 12:48 AM

Yep! Desiccant is fine --- provided you "keep up with it" --- otherwise it saturates and can literally become a humidity source when conditions change. Very similar to "indoor" carpeting in an observatory... which seems to mitigate humidity for a month or a year --- and then begins to stink of mildew and stale moisture tracked in on wet shoes and adsorbed from the atmosphere. A room-sized carpet can literally be holding quarts of water... poised to erupt and deposit on your lenses and mirrors!

 

Similar comment regarding permanent ~wall to wall~ carpeting in houses and cars - especially with dogs, cats, kids, diapers, food, and drink in the mix!  Tom



#6 GGK

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Posted 13 February 2024 - 06:32 AM

If you have desiccant packs in a gun safe, then the house will also be air conditioned, which really renders the desiccant irrelevant.

 

Desiccant should only be used as a stop gap measure once the scope is PROPERLY dry both outside AND inside.  It should be the last line of defence against damp, NOT the first.

 

The actual amount of water that desiccant packs can absorb is actually very small, which is why they should not be relied upon to dry anything and only be a last line measure.  Once the desiccant is saturated, which will happen quickly in a humid environment it is totally useless.  As a result they will need regular changing and recharging - something that loses is appeal very quickly after a couple of weeks.

 

Humidity a big problem, as well as stagnant air.  I have seen beautiful and expensive scopes ruined because they were not kept in a dry environment.  In one instance a brilliant 7" Mak which was kept in its original metal box AND with a desiccant pack, was totally ruined, scope, case and all by mould.  It was kept in a garage that had no ventilation and as with most garages, was not damp proof and not air conditioned.

 

High humidity is also a BIG problem for us here in Sydney.  My man-cave is a converted stand-alone garage which developed a damp problem soon after being converted.  This is also where I keep my astro gear and all my tools.  I struggled with keeping rust off my tools and lived in fear of how my astro gear was doing.  I spent a goodly amount of money on desiccant and made many packs to stuff into focusers and cases, but the desiccant lasted for only a few days before it was saturated and ineffective.

 

The single best purchase I have made for EVERYTHING in my man-cave was installing a de-humidifier.  I have its drainage hose bleed into the drain of the sink in the man-cave.  In just the first 24 hours that I had the dehumidifier running the air inside the man-cave totally changed.  The unit I have is a small one, enough for a room, low power consumption and it does an outstanding job.  I also have a small fan running in the man-cave to make sure air does circulate effectively through the room.  I no longer use any desiccant packs at all.

 

After an astro session in my backyard my gear is routinely soaked with dew.  I bring all my gear into the man-cave and leave it all open in the room and leave it to have the de-humidifier dry it out.  This is more important than you think as dew will be wicked into all manner of nooks and crannies of your scope, gear and mounts.  If you think your gear is dry because you no longer see any water on the surface, you are sorely mistaken.  It is this hiding and trapped water that accumulates over time and causes damp and mould problems.  Leaving all the gear, scopes, eyepieces, cases, EVERYTHING open for the dehumidifier to dry it out overnight draws out ALL the water, outside and inside of the kit.  Only then do I pack away everything.

 

Air conditioning does the same job as a dehumidifier, but installing an air-conditioner just for your astro gear needs careful consideration as it is power-hungry.  A dehumidifier uses a fraction of the power in comparison.  But an air-conditioner is also not a bad idea to help keep your gear cool during the day in preparation for an evening session, reducing both the cooling period (if any) and preventing thermal issues from say inside a personal obs.  Isolation and insulation of such a structure is also of major benefit for the effectiveness of this.  Remember, professional observatories are also giant cool rooms that are air conditioned so that these big instruments and structures don't become warm during the day - there won't be enough hours in a night for such instruments too sufficiently cool otherwise.

 

Alex.

I do the same in southwest Florida. 
 

Two dehumidifiers running full time in my storage area with condensate lines piped outside keep the room at 40%. Occasionally during the winter dry season, one will shut off automatically because the outside humidity dropped enough. 
 

I leave all cases open and caps off for a day after a night of observing. 
 

It’s the only thing that’s worked for me other than full time air conditioning. 
 

Gary



#7 Keith Rivich

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Posted 13 February 2024 - 12:53 PM

I do the same in southwest Florida. 
 

Two dehumidifiers running full time in my storage area with condensate lines piped outside keep the room at 40%. Occasionally during the winter dry season, one will shut off automatically because the outside humidity dropped enough. 
 

I leave all cases open and caps off for a day after a night of observing. 
 

It’s the only thing that’s worked for me other than full time air conditioning. 
 

Gary

I keep my 25" in a trailer at our dark site. Under a cover but still exposed to the humid air. I run a dehumidifier set at 45% and I have 4 gun-safe desiccant packs in the trailer as a back-up. They have been in the trailer for about 6 months and barely show any pink. 



#8 vincentv

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Posted 19 February 2024 - 02:20 PM

I'll rehash what others said with my own experiences.

You basically have 2 routes: passive and active.

 

-Passive: You use desiccant to keep things dry. A sealed box is *key*. How long the desiccant lasts is in direct proportion to how much air exchange is going on. Pelican, nanuk, seahorse and company are great for storage and transportation. I also use cheap sealed boxes from the hardware store. They come with a simple foam gasket. Without the gasket you're only wasting money.

I use larger packs meant for closets so they are oversized for the case. Keep a hygrometer inside to know when to "recharge". As mentioned above only put your things in it when you're sure they're dry.

 

-Active: In this case you will use electricity to control the relative humidity. I have used a golden rod to great effect. Make sure it's actually golden. The manufacturer has a cheaper line of heaters that are all black and reportedly they don't last as long (at least that's what the reviews said back then).

I used the golden rod with a dob that remained under a telegizmos cover. The heater was on the base, right under the primary mirror. The heater was connected to a humidity controller and finally the controller to a 500mA fuse since it was powered and unsupervised at all times.

The heater+controller trick is exactly how photographers store their equipment, the keyword is "dry cabinet".

Of course replacing the heater with a dehumidifier is more efficient for larger volumes.

With the heater you'll want a *little* air exchange. With the dehumidifier you can go all sealed but usually practicalities will limit what you can do.

 

I remember reading that you shouldn't go below 30% or 40%RH as that can crack the rubber bits.



#9 TonyInHonduras

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Posted 20 February 2024 - 12:34 AM

Wow I'm blown away by your kind and 8very informed responses bro my first CN post!

Since I live in a cave my wife runs, I cant take over a room, so ill build a case. Sealed with dessicant first, and if necessary add the heaters and a humidity control next if I cant keep the humidity down.

You folks are great!


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