PLA Smoothing: adding class to 3D prints

PLA Smoothing: Techniques

Why is there a need for PLA smoothing?

PLA smoothing is a must because 3D printing, using a PLA filament is done by the method of FDM that is Fused Deposition Modelling in which each layer of filament is printed one over the other in a systematic manner. This layer-by-layer printing causes, irregularities in the printing surface because print lines can be seen no matter how small is the layer height we set on our slicer. Hence PLA needs some post-processing and smoothing. PLA Smoothing will add to the presentability of the 3D printed object. At times, PLA Smoothing also reduces the friction among moving parts.

PLA Smoothing will characteristically involve the following methods:

Ways by which PLA smoothing can be done

Removing the Supports cautiously

It should be ensured that we have minimum support structures in our print. It saves both time as well as money. This is because less amount of filament will be required for the same print. It is extremely important to ensure that, the support structures are not made on the directly visible surfaces. Less support would require reduced processing.

But it is well known that printing without the help of the support structures is impossible, hence, one should carefully remove it by gently pulling. If required, one can carefully use a blade. Another means is to run them under warm water before pulling it. Use of soluble filament for printing the support structures is also advisable. One can keep the filament in a bath and the support structure dissolver without any effort. This usually works with the double extruder mechanism.


Sanding is the method by which, with the help of sandpaper we can easily get rid of the layer lines along with the leftover rough marks of the support structure. Sanding is not the ultimate step but quite often the starting step for any kind of smoothing process.

With the help of this one can level the uneven surface of the printed objects and make it rough before we finally give it a shiny smooth surface. There’s a variety of ways by which we can smoothen the surface, one of the very commonly used means is via sandpaper.  In the beginning, rough sandpaper is employed, later on we can keep on refining the sandpaper throughout the process. The roughness of the sandpaper decreases, as the number mentioned on the sandpaper increases. For example, for the initial knocking of layer, sandpaper numbered 120 is used. This number keeps on increasing throughout the sanding process.

Decreasing the layer height

In order to get a smoother surface, one can go to the slicer settings and decrease the layer height. Nonetheless, this process is usually not used as it has got various disadvantages attached to it. A major one being the drastically increasing of the printing time because of downsizing the layer height. The longer the print time, greater is the problem, as it leads to worping and filament jams. Moreover decreasing the layer height does not make the print completely smooth, there is still some form of smoothening required post printing.

Using Colour spray along with the Polyurethane spray

Using this method, one can easily improve the surface finish of the print. This spraying technique wily hides the printing flaws. One can also print with a larger layer height, using this method as the spray fills the gaps and gives a relatively smoother surface. However it is quite relevant to make sure that the color paint bonds with plastic and the polyurethane dries fast. After the spraying of every coat, the print should be kept under the fan so that each sprayed layer dries perfectly.

The downside of this method is that at certain times thick spray layer can also hide the details of the print. It should be noted that while spraying one should without fail cover their work desks properly as the spray is sticky in nature, making it hard to be removed from the surface.

Vapor smoothing

In the process of Vapor Smoothening, the printed object is kept inside a chamber. Below the bed of the chamber, a chemical is present which is usually isopropyl alcohol. The Vapor chamber consists of a nebulizer in the back, which creates a fine mist that covers the printed object and gives it a smoother finish. One can also set the timing of the vaporizing process depending on the size of the print and the requirement. The bed of the chamber on which the print is kept is of uneven surface so that printed objects can easily be removed otherwise it will stick to it.

The downside of this process is that it welds the functioning parts together, so after the end of the process, the parts find it difficult to function smoothly. The process done in excess can damage the details of the print, and can even lead to melting. Moreover, the container of the machine also has its restrictions, which is that big objects can not be inserted into it.  

Print with ABS

ABS produces fumes while printing which is highly toxic in nature. ABS is not eco-friendly and also uses Acetone. Acetone needs to be heated up, its vapors are exceedingly toxic and flammable so it should be handled with utmost care. Usage of the perfect amount of vapor and the timing of the process should be precise, in case it’s overdone it can lead to the melting of the print and destroy it completely. ABS is currently being replaced with other filaments because of its harmful nature.

Methylene Chloride

Methylene Chloride is a chemical that helps in smoothening the print. The chemical can simply be used by adding it to the spray pen or using a brush to coat the chemical on the upper layer of the print. It should be noted that the use of gloves is highly recommended for this process.

Using Heat Gun

The heat gun releases hot air, which results in the melting of the top layer of the printed object, reduces the layer lines, and ultimately smoothens it. However, if we keep the PLA in front of the heat gun for too long it can soften the print and can deform its shape. Hence heat gun should be used cautiously and not for too long.  Using a heat gun is not the smartest solution for smoothing but it is one of the easiest ways of leveling the surface of the printed object. 

A word of caution

It is advised to always wear a mask throughout the smoothing process. All the filaments of the product are made from plastic, therefore during the smoothing process, tiny plastic should be prevented from entering our respiratory system. Moreover, various other processes also require the use of certain chemicals for smoothing thus it is important that one carries out the entire process very carefully.

Also read: Tips to improve 3d print quality

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