To humidify or not to humidify

[HistoryTeacher]

Dear fellow collectors

I'm fairly new to this forum but I've been collecting German militaria (insignia, paper work, equipment and head gear) for quite some time now. Regarding my collection and the space where I keep it in, I really have my doubts and I hope you can help me with my problem.

Aside from the paper documents and photos, which I keep in an acid free folder from the German 'SAFE' brand, I keep my other items and some small books in 2 large showcases, in my study. Light and dust damage are not the issue, but temperature and humidity are. After reading some topics here I want to purchase the following things: a hygrometer, a thermometer and a de-humidifier.

I understand that I first need to find a way to keep the temperature constant (15-20°C) before installing a de-humidifier with hygrometer. What if the level of humidity becomes too low? Do I need a humidifier as well?

I keep some of my items in hand-made wooden boxes with a cotton base. I thought it was a good idea to prevent the items from dust and light because this is after all my study, a place to work as well. I've read something about the damaging effect of varnish, so should I replace the boxes by some acid free, aluminum ones?

http://militaria24.de/kassetten-koff...alu-/index.php

Greetings from Belgium

Karsten

[HistoryTeacher]

Anyone? Could use the help though. ;-)

[blinky]

Well, the first thing you should probably do is determine how much the humidity fluctuates where you have your collection. A fluctuation of a few percentage points shouldn't matter that much based on what you have and even a spike in one direction or the other shouldn't be a concern unless you have an item with dormant mold that might come out if the humidity is very high or an organic item that might split. Here in the northern US we have very dry winters and very humid summers. I find that running a humidifier in the winter and a de-humidifier in the summer is a good idea. It's great if you can maintain a constant humidity but in most environments that's not really an option....the best most of us can hope for is to prevent major spikes in either direction. Something to remember: the temps and humidity levels we like are the same for rodents and other pests. It's not a bad idea to always check for signs of bugs or creatures.

As for the boxes: painted or varnished wood (as well as just natural wood) can off gas so an inert box is best. One rule of thumb is that if the box is in an enclosed area like a cabinet and you can smell it when you open the cabinet, it's not a good box. The older the paint or varnish the less off gassing there is and it's not as big of an issue. One other thing: instead of using cotton use something like polyester (new made polyester, not recycled). This is inert and provides a better barrier between the container and the object. Cotton, being organic, can have some issues of its own.

It's easier to deal with these things in little steps rather than all at once....it can get to be overwhelming. Many of these items are pretty durable and as long as you protect them from extremes can be fairly forgiving. Checking the temperature and humidity once a day will help you catch an issue before it becomes a problem. Being aware of the environment around you will do the same. If you're hot and sweating and don't have air conditioning in your house, there might be a problem developing you'll need to address. If it's hot and humid outside but you have air conditioning, you need to remember that A/C can dry the air out in the house and you might need to check the readings around your collection a bit more often.

[Paul R.]

Blinky is correct... I’m just curious when you say that light and dust are not, and issue why they are not an issue? Yes, an investment into a good dehumidifier is a step in the wright direction. Purchasing a good humidity gauge
is a very good investment as well. I prefer keep the humidity at 43-45% 24/7-365. Other people say up to 55% is okay. In most museums that I work at humidity is held at 43-45%. I find that anything over 48% on paper and some leather mildew can start. Most noticeable when the room temperature is over 78 degrees F any item with mold spores will start to appear and spread on your items.
Low humidity can cause damage as well. Anything below 35% can cause a steady drying out on items such as wood, leather, rubber, bakelite, binding on books etc.
Yes, going back to your first statement light and dust are issues. Light can cause fading of paper, printed materials, leather, fabric, wool, plastic, artwork, and others material. An old experiment showing how light can fade something.

Take a newspaper and a rock. Place the newspaper on a table facing direct sunlight. Put a rock about the size of your fist on top of the newspaper. Leave in in the sunlight for two weeks. In two weeks remove the rock and check the fading that occurred. Not putting light on you items are best, or invest into the new LED lights.
Wood boxes or wood frames that are pre made are usually varnished with a cheap sealer or varnish. Usually they can out gas toxic fumes. If you have a pre made wood item, and you are not sure of the sealer that was applied to that item. Sand off or apply a product that is called a polyurethane usually a clear choice is best. This product is hard as a rock and once it dries there is no out gassing of fumes.
Yes, I like aluminum cases not as pretty was wood ones, but no out gassing on these styles of cases. Just be sure the interior has acid free materials in it

[HistoryTeacher]

Thanks Paul and Blinky for your advice! In my first post I said dust and light damage are not an issue. Concerning the light: my study has shutters and as I don't work for many hours in this room, UV rays from the sun won't have a big impact on my collection. About dust: I try to keep my showcases and the items in them as clean as possible. No sign of mold or bugs yet. Maybe a little lavender could to the trick, just in case of any hungry bugs...

A little update today: I bought a digital hygrometer/ thermometer. The average humidity in the room fluctuates between 36 - 42%. I notice that if I keep the temperature towards 66°F (19°C), the humidity is somewhat higher. Colder air holds more moisture? The room is by the way on the second floor, I guess the air is drier there than for example in the basement.

Is this humidity level sufficient or should I buy a humidifier to push the average humidity to a constant 43-44%?

Concerning the wooden cases, I think I will replace them in time by aluminum ones. Replacing the cotton by polyester is my next step. Like you said Blinky, small steps :-).

[blinky]

That's a little low; metal objects like less humidity but leather, wood, etc. may start to slowly dry out if it was like this 365 days a year. A good humidifier (like a dehumidifier) is a good investment if you have the money to put towards it. You will have to weigh the benefits against the negatives though. A humidifier can be a pain in the butt. They need to be cleaned and flushed out on a regular basis. If you have minerals in your water that can damage the humidifier over time. If it doesn't have a built in hygrometer it can keep running even when it shouldn't. You have to be careful where you place it, the mist that comes out of most can coat objects around it with any impurities in the water. Since this is just a room and not an entire house you wouldn't need a very big unit.

In a way I'm more concerend about an environment being too humid (leading to rust and mold).

[Paul R.]

Blinky is correct again. Yes both of these units can be a pain in the a** to drain, and clean out on a regular base. If the humidity drops 10 degrees below the desired amount for more than a week. I would add humidity to the room. On the other hand don’t allow humidity to remain high more than 3 days at most

As far as insects you may also add cedar fragrant to you storage area as well, or cedar wood chips work well.

Yes, of course small steps are the best way to go. If you got any concerns you can always post them here. Sorry I did respond right away. I travel a lot at times.

[HistoryTeacher]

Thanks for your advice again! Today, the hygrometer shows an average humidity of 32%. Seems to drop lower each day. Better start browsing the web for a good humidifier. And maybe a better hygrometer since this thing only cost $13 (10 euro)?

Any good brands that I should check out? I don't know if it exists in the States, but the 'Conrad' brand seems to have a lot of equipment concerning humidity.

[Paul R.]

I haven't heard of the Conrad brand, that doesn't mean that they are no good. I have found that many times a bit more expensive one might be a better choice being a bit more accrete over the long run.
I would not rush out to buy a humidifier, or dehumidifier just yet. I good idea is to grab a piece of paper and everyday record your findings. Then average them out over the period of 10 days. Humidity can change every 15-30 minutes in any given room.
Just our body alone gives off humidity. If the range is not too severe a small fan will move humidity around and lower the temperature a bit ghanging the humidity levels.