Is everything backwards?

Sometimes you see all this effort in an industry like this and everyone accepts it:

"All filament must be kept dry."

I dunno about that. Should we accept something like this without examining it first?

* Many people find that PLA behaves better when it's lubricated.
* Many assume that a roll of filament left outside of its bag has gone brittle because it's absorbed water vapor from the air.
* PLA is polyactic acid made from corn starch and I've also heard of vegetable oil.
* Water in theory messes with the monomer chain of polyactic acid. Hydrolysis is one of the methods of recycling PLA.

I'm now printing the end of a roll of Robo black PLA and it's gone super brittle since it's been on the desktop and out of its packaging for a month now. The slightest pressure will break the filament itself.

The general wisdom of the industry suggests that it's gone bad because it's absorbed water. That's certainly possible since corn starch plus water changes its behavior significantly, especially when heat is involved.

But what if we're thinking about this wrong? What if the problem is that the PLA is losing something like those double-carbon bonds due to oxidation? Now remember, we probably own cars which have tubing and plastic surfaces. For decades, I've returned EGR rubber vacuum hosing to its "like new" luster by lubricating it with WD-40.

We know that UV rays, oxidation and ozone break some of the carbon chains in rubber and plastics. Keeping rubber/plastic dry isn't the solution since air includes oxygen which is a likely culprit. Just like in the car industry where we're using Armor All and WD-40, we might want to choose a wet approach to fixing this. (Covering something in oil is a way of preventing oxidation.)

Armor All is made from water, silicone, diethylene glycol, glycerin and other things. At least for rubber/plastic found in cars, water isn't a problem.

Keeping something dry doesn't prevent oxidation, in fact it promotes it in plastics and rubbers.

Where I'm going with all this is that maybe building a dry box for filament isn't the answer; what you really need is a wet box which includes a fair amount of coconut or canola oil or say, WD-40 (which is fish oil).

Although canola seems to be the main filament lubricant of choice, coconut oil has the highest percentage of saturated fat at 87% so it should be the least likely to go rancid.

With this in mind, I intend to build a wet box for my dual-spool filament holder and to incorporate coconut oil or WD-40 into the design.

 

These spools are coming in bags with desiccant and no air in them. It's that "no air" part that I'm talking about as well.

 

You're basically making my point by reiterating what the industry believes and has come to accept. I'm asserting that oxygen causes problems.

So I'll do some testing in this area and eventually report back if I'm getting anywhere on that.

 

Will do. It's definitely protected from UV at the moment where it's sitting but it's super-dry here in San Diego most of the time and especially thoughout the summer months.