DIY Humidity Chamber

Looking inside the DIY humidity chamber

I was very impressed and inspired by a LOT of last weeks Chris Clarkson workshop, however one seemingly simple tool we made blew my mind. This is a fantastic idea for any conservator, but especially those working in small workshops. Part of Chris’ course included the humidifying and controlled drying of flat parchment documents. To do this you need a humidity chamber. If you are unable to afford the some $5,000 for your own super-duper humidity chamber you might consider this expanded polystyrene model.
The real beauty of this is you can make it to a reasonable size for your workshop. The polystyrene has an insulating effect and unlike some other humidity chambers water droplets do not accumulate on the ceiling and walls.  This chamber is relatively large and to be honest a little bit in the way in this workshop, but it was necessary to make it this big to accommodate the parchment charter we were humidifying.

The chamber requires a piece of expanded polystyrene, plumbers tape (duct tape), a reasonable weight sewing thread, a cork, two toothpicks, an ultrasonic humidifier and an electronic hygrometer.

Cinzia punching the holes in the side walls for the shelf

First, cut the bottom, top and two side walls of the chamber to size. Next decide how many shelves you want inside your chamber, ours had one. On the outside of both side walls attach a strip of plumbers tape at the height you want to place your shelf strings. Make sure the strips are in the same place on each wall so your shelf is level. Mark a line down the middle of the plumbers tape on each wall to use as your guide to punch your sewing holes, our holes were 2.5cm apart from one another. Pre-punch the holes on the plumbers tape side using an awl. The tape insures that the thread does not start breaking through the polystyrene.

Sewing the thread shelf

Next attach the side walls with several pieces of plumbers tape placed perpendicular to the seam. This is a rough attachment, a long strip will be added once the shelf threads are in place. Make sure you place the walls on top of the base not on either side.

Now comes the fun part. You need to sew the thread in and out of the walls to create your shelf. It helps to have one person unwinding the thread, someone sewing, and a third pulling the thread so you can make the shelf with one really long piece of thread.

Toothpick used to hold thread in place at start and finsh of the shelf

Once the shelf is complete take a toothpick and attach the thread to the starting point of the shelf. Tighten all of the threads and use a second toothpick to hold the thread taught at the finish.

Attach the top in the same way you attached the side walls. Use several pieces of plumbers tape perpendicular to the seam for a rough attachment. Once everything is lined up and in the right place use a strip of tape along the length.

Chris using a broom to hold the back wall in place while Jenny is applying the plumbers tape on the outside

The back wall is cut to fit in the chamber. Once cut to size a hole should be cut in the upper right or left hand corner to fit your ultrasonic humidifier hose. It is best to cut it a tiny bit too small so the seal is tight. Attach the back wall on all four edges using plumbers tape. It is helpful to have someone pushing on the wall from inside the chamber to prevent it from falling inside when applying the tape.

Door attached with cork in place

Finally you need to cut the door to size. Unlike the back wall which fits inside the chamber, the door is attached to the top piece of polystyrene and a plumbers tape hinge is used to open and close. Before attaching the door make a circular hole to fit your electronic hygrometer probe. A cork will be used to fill the space when you are not using the hygrometer.

Chris commented that carrying around something this large makes you feel super strong like Tarzan. The light materials and cleaver construction allow you to move it around your workshop as needed…empty of course.

Tarzan carrying the humidity chamber

To get it going turn on your ultrasonic, have the door shut and your electronic hygrometer in place. Wait for the RH to reach the percentage you want, once it’s there turn off the ultrasonic, place your item in the chamber and shut the door. Measure the RH once the item is in and if needed turn on the ultrasonic again and wait for the RH to get back up where you want it. Check the RH from time to time using the ultrasonic if the level has dropped.

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