That lamp and it's PLA parts will out live you.
This is the answer I get from most people. But then I read about parts falling apart after 6 months so I get skeptical. Thank you for weighing in though I’m leaning towards PLA since it’s easy to work with.
Hydrolyzing is the process that degrades PLA polymers. Poly-lactic Acid is made from glucose that is converted to lactic acid. Then one H2O molecule is removed to form monomers. Then heat is applied to snap the monomers end to end to form polymers. So, it really wants that H2O back but can't get it unless there is enough energy; mostly heat and moisture also has to be present. Bacteria can also chop them apart but again, moisture is needed just for the bacteria itself.
In a lamp, there is heat. Degrading is more possible. It is not very likely, PLA can survive in normal room conditions for years. Best way to protect them is to coat the part first, Paint or clear coat. The latter is standard stuff, you should always have clear coat ready: any parts that are made to be handled, anything to do with hygiene or food, anything that has to endure moisture or heat, or UV: clear coat.
Also if visual quality is extremely important but you also need to do some post processing: clear coat, in that case you can't even touch the part with skin but have to use disposable gloves, and spray it before post processing to prevent your dead skin cells don't end up between layer lines. The outer surface is like it is made of squishy tubes on top of each other, and there is a crevice between each of them. Once dirt gets inside it is VERY difficult to remove it.
So.. get some clear coat. If you live in an apartment, get yourself very large cardboard box, big enough to put both hands inside WITH the object and make yourself a miniature paint booth. Spray the walls of the box lightly with water before use so the walls can capture the very tiny flying particles.
Thank you that is super helpful. I never knew the human body and PLA had so much in common. Clear coat is an easy solution and makes a lot of sense to protect the parts.
I think that knowing a bit about the chemistry makes it so much clearer, pun intended. Fortunately PLA is super simple stuff, it is just "dried" lactic acid. Wonderful material, truly. If you ever happen to cast or do a re-flow you will be surprised how freakishly hard and strong it is. It is in the same class with polycarbonate when it is uniform material. When printed it only weakly bonds to the previous layer and there is a ton of voids left behind. It is melted line of plastic very rapidly attaching to a line of solid plastic. It is so hard that you can use it to make musical instruments and parts.