PLA is cheap, easy to print, and highly versatile—but it’s not a perfect filament. For a slightly higher material cost (and a little extra work), you could print with PETG instead.

Here are some instances when you might want to pick PETG over PLA.

When your print is going outside

PETG offers superior durability

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Broadly speaking, PLA is unsuitable for prints that are designed to live outside. This isn’t to say that people don’t print objects from PLA and use them outside, but if you want an object to last, then you’re better off picking an alternative material like PETG.

PETG will better withstand outdoor conditions, especially when placed in direct sunlight. UV rays can degrade and discolor PLA prints far quicker than those made from PETG.

When your prints need to withstand higher temperatures

It’s all about the glass transition temperature

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Compared to PLA, PETG holds up better when the temperature is higher. PLA has a glass transition temperature of around 60ºC, which is the temperature at which the material starts to deform. By comparison, PETG doesn’t start to deform until around 85ºC.

While this might sound like a small difference, over time it adds up. Consider objects you might print and leave inside a car, which are subjected to full sun and baking temperatures over months or years. PLA can even start to soften when exposed to direct sunlight outside on a hot day.

When impact resistance and strength is more important

PLA is brittle

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PLA is a highly brittle material that is more likely to shatter than PETG. For objects that might face sudden impacts, like drone shells or flying discs, PETG is more likely to survive. In terms of overall strength, print orientation will make a huge difference too (even the toughest materials need to be printed correctly).

PETG is better in the workshop

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In environments where your prints are likely to be exposed to chemicals and solvents, PETG is the better choice. One such example is in a workshop, like if you’re 3D printing accessories for power tools and are concerned about what those parts will be exposed to.

When you want supports to come off cleanly

Combine filaments for best results

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This is less about choosing PETG over PLA and more about cleverly combining your filaments for best results. Supports are an inescapable part of 3D printing; they prevent parts from sagging and allow you to print overhanging sections where the model won’t support itself.

Unfortunately, supports are often difficult to remove and can leave unsightly marks in your model when you pull them off. One way to remedy this is to use PLA supports in PETG prints (or vice versa if you want to print with PLA). These two filament types don’t adhere to one another too well, allowing you to easily remove your supports once printing is complete.

Things you should know about PETG

It’s not perfect

PLA is the easiest material to print with, but PETG can be more challenging. The latter is more prone to warping and cracking, particularly as the filament cools and sets. Slowing down this process can help, and a printer with a heated chamber can help considerably. A heated print bed and enclosed printer are better than nothing, but expect to struggle a little more on an open printer that lacks all of these things.

PETG should also be thoroughly dried before use, on account of its tendency to cause stringing. You’ll want to make sure you store it properly to prevent moisture buildup from necessitating another dry cycle. Unlike PLA, which is dried at 45ºC or thereabouts, PETG dries best at higher temperatures of around 65ºC (which not all dryers can manage).

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By comparison, PLA feels like printing on easy street. It doesn’t warp (though it can benefit from a heated bed to prevent adhesion issues), and a heated chamber is unnecessary. PLA is only likely to cause stringing when the moisture content is too high, and while you should dry it before use you’re more likely to get away with using PLA straight from the factory.

Lastly, there’s price and availability. PLA is cheap and very popular, which means that there’s a wide variety of colors, styles, and blends available. PETG can be marginally more expensive (though not always and nowhere near as pricey as some of the more exotic filaments), and you’ll find a narrower range of finish and color options compared with PLA.

This isn’t necessarily a big deal, since many of the reasons you’d pick PETG over PLA are utilitarian in nature anyway.

PLA still reigns supreme as the filament that most 3D printer owners should stick with for most prints, but it’s never a bad idea to have some PETG on standby for items that need a bit more durability and heat resistance.