About a month ago, I brought a 3D printer from Chicago to Recife, Brazil – smack in the tropics and right on the ocean.  A glass of cold water gets covered in a film of moisture in about 10 seconds.  The cool ocean breeze hides the fact that it is humid here, as my rusty tools can attest.

This is why I missed the class on how PLA 3D printer filament soaks up water like a sponge.  I saw the results of this when I tried printing a luggage tag for a friend.  The first attempt (shown on the right side of the picture below) was awful.  Aside from appearance, it was spongy since the filament didn’t fill in the shape.  Also, the filament jammed in the extruder, and I had to take everything apart to fix it.  Twice.


Once I figured out the problem, I found a quickish solution, and the new tag came our perfectly as you can see from the left side of the image above.

First, when PLA (or ABS, for that matter) sucks up water, it expands the filament, leading to extruder jams.  Second, as the filament moves through the heater, the absorbed water turns into steam that keeps the filament from extruding properly.  The resulting print was spongy because of all the holes caused by the steam escaping the print nozzle.

So – how do you fix this?  First, move to Arizona.  OK, just kidding.

I took the bad spool of filament and put it in the oven at about 60C.  You don’t want to get much hotter than this because the filament will soften, and you’ll lose the whole roll.  As it was, the spool itself warped pretty badly, but the filament dried our pretty well after 2 hours in the oven.  With no further protection, it worked pretty well for about a week.  (Did I mention how humid it gets here?)

The next step is to keep dry filament in an airtight plastic container with reusable dessicant packs that keep everything inside nice and dry, and can be recharged when they lose their oomph.  Amazon sells several kinds, and also sells low-cost digital thermometers with humidity gauges so you can see how nice things are in your box.

My friend, Bill Steele, from Polar3D, had another great suggestion.  Use a big enough box to let you run a rod through the sides (a toilet plunger handle works well) to let the spool of filament turn.  Then, put a tiny hole in the lid through which you can get the filament out and feed it to your printer.

While humidity is not a problem everywhere, it is a challenge in some parts of the US, so pass this blog entry to your friends who might benefit from it.  I spent a week puzzling this out, and I’d like to save time for those who might benefit from these ideas.

Now go print something outrageously fabulous!