Why does Drying PETG-CF Reduce the Layer Bonding?

I am experimenting with carbon filled PETG, and I am getting confusing results… I have printed a few brands out of the box, and then dried them at 65C for 6 hours in a food dehydrator (checked with a digital thermometer), and while the dried filament is up to 50% stronger in the Horizontal (XY) directions, the layer bonding decreases when dried… I am finding about a 50% strength loss in the Vertical (Z) direction when the filament is dried…

Can anybody shed some light on this, or have you experienced this yourself?..


I find quite the opposite, drying increases the bonding and strength. I typically use 55ºC for 24-48 hours with a fan and desiccant. I think many don’t dry for long enough. Past that I can’t explain why you are not seeing the same. I only dry filament that needs it however, if my test prints fine I don’t bother.

PlA in particular (not petg) doesn’t like repeated heating cooling. It is why it isn’t the best at recycling it has a limit how many times it can be remelted. I almost never need to dry PLA occasionally not regularly.

That 55C for 24-48 hours, do you use that for PETG?.. I’m just following the manufacturers instructions for drying CF-PETG, in fact about half of them say only 4 hours…

I am finding that fillers (carbon, wood, silk or matt) really reduce the layer bonding… not unexpected…


Yes PETG, ABS and ASA. It is just what I have always done. There are manufacturers recommendations? Never seen any. It was based off a scale and making beef jerky for years. 4 hours doesn’t dehydrate anything. I think that is marketing foolishness, it just is long enough to tinker relative humidity numbers not actually make a difference.

Some fillers for sure, that includes pigments as well. Some pigments are more abrasive too. It depends on the manufacturer they use different pigments in varying amounts, some terms have little to no meaning it is just marketing.

I wonder at fast filaments, early testing it is not demonstrated to have higher flow or work better at speed. I ave not bothered yet myself.

PLA+ what is the plus it could be something or nothing at all, it is a marketing tool often.