Blobs and 3D print zits on the outside of your model can seriously affect the looks of print. Here are a few possible causes how you can cut down on these 3D printing artifacts.

Blob and 3D printing zits are another case of excess filament on your print. There isn’t usually a large amount of stringing and it only happens on some areas of the print.

Often caused by retraction settings, additional filament blobs out and onto the print.

Z-Hop (lift nozzle before retraction/travel), a very popular feature in most of today’s slicers can encourage blobs right at the retraction point. There’s two ways to go about this: either try increasing your retraction or disable the Z-hop.

At the point where the layer change happens, a small blob will appear, the so-called Z-scar (or ‘Zipper’). It is not always possible to eliminate the Z-scar entirely by adjusting retraction settings, but modern slicers give you some choices where this Z-scar appears: the default is usually for the Z-scar to appear randomly or where the slicer thinks it would be best to optimise print speed.

Usually you get a way cleaner looking print if you instead pick a specific less noticeable location for the Z-scar yourself. Like in a corner of a print, or at least somewhere in the back. Also choosing a specific location for the Z-scar will prevent the z-scar from splattering 3D printing blobs all over the print and confines them in more or less straight line along the Z-axis.

3D printer blobs and zits also appear on the surface of your print in random locations if your filament absorbed too much moisture. The steam building up inside the nozzle will make the filament pop at random times which will squirt out additional plastic (then followed by a dent because of lack of filament in the nozzle). Try drying your filament before printing to remove any moisture causing dent. To prevent moisture in the future, ensure you’re storing your filament correctly in an air-tight sealed bag with freshly charged desiccant, in a cool dry place. Do not leave filament out for longer than during printing.