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DEET and the Questar

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#1 Gregory Gross

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Posted 07 August 2019 - 02:02 PM

N,N-Diethyl-3-methylbenzamide (DEET): it's the smell of summer.

Reading the section in the Wikipedia article about DEET's effect on materials, I see that it's also something that acts as a solvent on watch crystals, painted surfaces, and other things. I've heard that DEET is not kind at all on optical coatings.

With the mosquitos getting hungry, aggressive, and numerous, observing on hot summer nights without applying some DEET-based bug spray is a prescription for a ton of bug bites.

This is my first summer with my Questar. After applying bug spray before my observing sessions with my other scopes, I haven't worried about the effect of whatever DEET residue is left on my hands even after washing them a few times. But I have to confess that I've been a bit paranoid about whether I might damage the finish of my Questar if I start handling it with even trace amounts of DEET on my hands.

Has anyone ever encountered problems with, say, fingerprints being etched onto the painted surfaces of their Questars or any other damage after applying bug spray? I'm not sure if I'm being appropriately careful or overly paranoid.

#2 Jim Waters

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Posted 07 August 2019 - 02:13 PM

I have had problems with DEET getting on my glasses once.  It caused damage to the plastic lenses.

 

You should never use stuff like this around optics.  When I apply DEET I always walk some distance away from my equipment before applying it.



#3 Napp

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Posted 07 August 2019 - 02:14 PM

Deet is harmful to optical and other surfaces.  Instead of deet products try products with picaridin as the active ingredient.  Works as well as deet and is not harmful to optical and other surfaces.


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#4 Jim Davis

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Posted 07 August 2019 - 02:14 PM

I use Picaridin when dealing with astro equipment. Works about as well as DEET, but isn't a hazard to plastics. I would still keep it off as much of your equipment as possible. DEET is still the best when dealing with mosquitoes.


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#5 terraclarke

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Posted 07 August 2019 - 02:26 PM

What about burning a citronella candle (with a light shield of course) nearby but downwind at sufficient distance so no smoke residue gets on the instrument?



#6 ngc7319_20

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Posted 07 August 2019 - 02:43 PM

What about burning a citronella candle (with a light shield of course) nearby but downwind at sufficient distance so no smoke residue gets on the instrument?

My concern would be that if the smoke is going downwind, so are the active ingredients.

 

I use nitrile gloves when applying DEET (away from equipment), and then throw the gloves out after application.  I'll wear some light weight work gloves while observing to keep bugs off hands (no DEET on hands).


Edited by ngc7319_20, 07 August 2019 - 02:44 PM.


#7 sturdy beggar

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Posted 07 August 2019 - 02:49 PM

Vostok.....

The previous posters are right on target. DEET will harm various surfaces, especially plastic. I will also give everybody a heads up on another potential problem. NEVER, NEVER place any optical equipment in close proximity to those little air freshener trees you hang from your rear view mirror. I found out the hard way when I discovered a Nikon camera lens that had been in a confined area for some time with an open "tree" package that I didn't know was there. The fumes or vapors attacked the lens coating and ruined it. I'm guessing there is enough air circulation and exchange to keep this from happening in your car.

Be careful.


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#8 John Noble

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Posted 07 August 2019 - 02:51 PM

Deet is harmful to optical and other surfaces.  Instead of deet products try products with picaridin as the active ingredient.  Works as well as deet and is not harmful to optical and other surfaces.

 

Another vote for picardin-based products, it smells nice too.



#9 agmoonsolns

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Posted 07 August 2019 - 04:12 PM

It's really hard on human beings too, we get Deet cases in the ER and it's not something I would want to mess with unless I had to. It's like one of the doctors said, you need to balance the risk from the chemicals with the risk from mosquito-born illnesses. Keep it the heck away from mucous membranes - nose, eyes, mouth, etc. and wash your hands really well. 



#10 MikeMiller

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Posted 07 August 2019 - 04:28 PM

What about burning a citronella candle (with a light shield of course) nearby but downwind at sufficient distance so no smoke residue gets on the instrument?

If it was downwind, it would not have much of an effect. I would be concerned about the wind changing and blowing on to the optics.

 

Also, I recently read this article about a study that suggests that citronella isn't effective at all.

 

https://www.sciencem...ronella-candles



#11 Napp

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Posted 07 August 2019 - 04:47 PM

I did not find citronella very effective.  If you aren’t in its smoke it’s not going to work at all.  My club recently had a lecture by an expert on mosquitoes.  He said the only effective repellents are deet, picardin and some eucalyptus based natural products.  However, the few natural products that work require frequent reapplication.  What he said agrees with my personal experience in the mosquito infested swamps of Florida.


Edited by Napp, 07 August 2019 - 06:01 PM.


#12 agmoonsolns

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Posted 07 August 2019 - 04:54 PM

Is it just me or have the mosquitoes been much worse than usual this year? 

 

One thing I have found that works is having a constant breeze or a small fan moving air and dispersing our scent/CO2 so they can't find you really helps. Humid, still air results in massive mosquito swarms, turn on the fan and they almost all go away. They'll hang out in a cloud downwind where the effects of the fan end so be careful where you aim the fan.


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#13 Mike E.

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Posted 07 August 2019 - 05:05 PM

Avon "Skin so Soft" lotion has something in it which mosquitos and other bugs seem to dislike. It works for me. smile.png


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#14 Gregory Gross

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Posted 07 August 2019 - 05:19 PM

It's really hard on human beings too, we get Deet cases in the ER and it's not something I would want to mess with unless I had to. It's like one of the doctors said, you need to balance the risk from the chemicals with the risk from mosquito-born illnesses. Keep it the heck away from mucous membranes - nose, eyes, mouth, etc. and wash your hands really well.

It takes me absolutely forever to get through a 6 fluid ounce bottle of DEET-based OFF! bug spray, so I'm thinking that I'm not overdoing it. Spray one arm front and back, rub it across. Spray the other arm the same way. Both legs if I have shorts on. Spray some on my hand and rub it across the back of my neck. Maybe spray a little on my t-shirt (I wear old, junky ones when I'm applying DEET) on the backside of my shoulders. And that's it.

 

My club recently had a lecture by an expert on mosquitoes.  He said the only effective repellents are deet, picardin and some eucalyptus based natural products.  However, the few natural products that work require frequent reapplication.  What he said agrees with my experience in the mosquito infested swamps of a Florida.

Picaridin-based products (e.g., Sawyer’s 20% Picaridin insect repellent) seem to require re-application only every 12 hours. I have to confess that I've never heard of picaridin before -- might be worth a try.
 
 

Is it just me or have the mosquitoes been much worse than usual this year?

Yes, that is what I've found at least here in the Pacific Northwest. We had such a wet winter that I imagine mosquitos have thrived especially well this year.

#15 Reid W

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Posted 07 August 2019 - 05:43 PM

I was using the deet towelettes. ...  when I finished, I just stuck it in my pocket.  Later I was using a red light, and put it in the same pocket. 

 

Pretty much melted the plastic.

 

Glad it was just a redlight.



#16 Gregory Gross

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Posted 07 August 2019 - 05:49 PM

It amazes me that DEET doesn't turn the plastic bottles it comes in to goo. The bottle I have is made out of HDPE (high-density polyethylene), which seems to be impervious to DEET.

#17 Jim Davis

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Posted 07 August 2019 - 06:01 PM

It amazes me that DEET doesn't turn the plastic bottles it comes in to goo. The bottle I have is made out of HDPE (high-density polyethylene), which seems to be impervious to DEET.

DEET doesn't dissolve every type of plastic, just certain ones.



#18 Alan French

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Posted 07 August 2019 - 06:03 PM

We had a bottle of Deet tip over in a cubby in my wife's previous car. Did some damage to the plastic.

 

I will absolutely not use Deet near any expensive item, including cameras, telescopes, and binoculars. 

 

In spite of the continuing reports of mosquito activity around here being "extremely high (9 or 10 out of 10)" they have not been very troublesome on our clear nights, which have been cool and breezy with low humidity. Early July in the Adirondacks was a different story.

 

Clear skies, Alan


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#19 terraclarke

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Posted 07 August 2019 - 07:00 PM

If it was downwind, it would not have much of an effect. I would be concerned about the wind changing and blowing on to the optics.

 

Also, I recently read this article about a study that suggests that citronella isn't effective at all.

 

https://www.sciencem...ronella-candles

 

It was merely a suggestion. I don’t use citronella candles where I observe because I generally don’t have that many mosquitoes around to consider it a problem. However they do seem to hover about when we have a gathering/dinner on a summer evening on the deck and we often place a citronella candle on or under the table and it’s been pretty effective. Nor have have I encountered enough of the pesky creatures when observing to feel the need to use DEET, Off, Cutters other repellants. (I hate the repellent on me more than the bug bites.) I do however make it a practice to not use any cologne if I am going out observing. Another remedy I heard about but never tried is the use Bounce fabric softener sheets. I’ve been told you can rub them on your skin or put them in your pockets and mosquitoes will leave you alone. I haven’t tried that, just heard about it. Mosquitoes pretty much leave me alone anyway. I can go through an entire evening and only get one or two bites at most, usually none. And in summer I observe in shorts, tanktops, and flipflops! I guess they don’t like me? I consider that a good thing! Noseeums and chiggers are another story. The good thing about noseeums is that the bite goes away in twenty or thirty minutes. The bad thing is, when they’re around, they’re in clouds and you get totally bitten up! Chigger are much worse. Their bites last for days! But if you stay away from brush and tall grass chiggers will generally leave you alone. For noseeums, a Benadryl pen is indispensable! It takes the burn and itch away almost immediately.



#20 sydney

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Posted 07 August 2019 - 10:21 PM

I have a “sacrificial” baseball style hat that I spray with DEET when hiking, running, or observing if mosquitoes or black flys are bad. I just lay it on the ground, spray it, and put it on without letting my fingers touch the top.  Works well.  The hat gets stiff and ugly over time.  For observing, however, I prefer to just put on a regular cap and overshirt and skip the bug repellants.  The smell disrupts the harmony of observing more than the pesky bugs.  



#21 SJTill

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Posted 08 August 2019 - 12:41 AM

have a “sacrificial” baseball style hat that I spray with DEET when hiking, running, or observing if mosquitoes or black flys are bad. I just lay it on the ground, spray it, and put it on without letting my fingers touch the top.  Works well.  The hat gets stiff and ugly over time.  For observing, however, I prefer to just put on a regular cap and overshirt and skip the bug repellants.  The smell disrupts the harmony of observing more than the pesky bugs.

 

If you’re going to do that, it’s better to use permethrin liquid (also from Sawyer’s) to spray on clothes—hats, shirts, pants, socks—you wear around mosquitoes. Dries so it doesn’t smell, doesn’t make the clothing sticky or stiff, and lasts through numerous washings. Nontoxic. 

 

I use both permethrin on clothing and picaridin (Natrepel) and never use DEET due to noxious odor and, more important, potential neurotoxicity.



#22 sydney

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Posted 08 August 2019 - 06:04 AM

From: https://www.consumer...mosquito-bites/

 

“ None of those shirts, however, were as effective in our tests as was a shirt sprayed with the repellent deet. Note that while permethrin is often called a repellent, it works mainly by killing or incapacitating mosquitoes once they land on you, not by preventing them from landing in the first place. And even when wearing the shirts, the manufacturers say you should apply a repellent to your exposed skin, too.
Did the Shirts Work?
The permethrin-treated products did kill or incapacitate many of the mosquitoes that landed—but in some cases that didn’t happen quickly enough to prevent bites.”

 

 

Also, while permethrin is relatively safe for humans, it is known to be highly neurotoxic to cats and fish.

One of many references: https://www.ncbi.nlm...les/PMC5598406/



#23 Kevin Barker

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Posted 08 August 2019 - 05:49 PM

Mosquitoes are fierce in Auckland, New Zealand. Particularly after rain as the mosquitoes breed in drains and plant container bases etc

 

I am sometimes literally driven inside by the **** things.

 

I started using a Pyrethum spray which I use to spray the foliage of grass trees, shrubs etc a few hours before observing. This does reduce the mossies quite a bit. I also add 5 ml of white spirit to the drains that are close to my observing site. Our drains go into soakholes as I live on a Volcano (Maungakiekie or One Tree Hill) This also helps.

 

I also find using 3 mosquito coils spaced about 5 m to further reduce the wee biters if the first two interventions are not enough.

 

This reduces the need for DEET.  On most nights this allows me to observe without the biting and annoying buzzing.




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