What do you do when you want to print a complex object that requires support? If you’ve got a design that incorporates a certain amount of overhang and/or details, then the answer to your problems will be some kind of support filament.
Perhaps the most popular and main-stream used support material is PVA dissolvable filament.
PVA really allows to you to push the envelope in your designs, so that you can get a glimpse of the full potential that the future of 3d printing holds. In this article were going to take a close look at printing with PVA, examining what it is, when to use it and how to print with it in order to get the best results.
PVA stands for polyvinyl alcohol. PVA is a synthetic polymer that is strong, non-toxic, biodegradable and, most importantly, water soluble. This ability to dissolve in water means that PVA is used commercially in everything from laundry and dishwater detergent packs or pods to eye drops.
In 3d printing, PVA’s water solubility makes it an excellent tool that provides support to models that include intricate detailing or involve overhanging features.
As you know, a 3d printer starts printing an object from the bottom up. This means that if you have a design that incorporates overhangs over 45 degrees or bridged areas in your model that don’t have any underlying material, you’re going to run into problems. After all, your printer filament is subject to the law of gravity. It can’t be extruded onto thin air.
If your filament is low temperature and cools fast (ahem, like our PLA) - you can often make small bridges and overhangs without support and you'll get a nice clear bridge (like on our 3D Benchy below). But anything larger and you're likely going to need supports.
Got good Benchy? Printed without support, our PLA bridges nicely - but larger bridges require support. For reference this Benchy is 6cm long
PVA solves this problem by providing the support medium for these overhangs. Your printer first lays down a layer of PVA support material underneath the area where the overhang will be.
Once the PVA 3D printing filament is in place, your printer is able to continue laying down the upper levels of your model. By using PVA 3D printer filament, you avoid the warping or total collapse that would occur if the PVA wasn’t there.
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So why use PVA over other support materials?
Well, getting rid of the PVA support material once you’re done printing couldn’t be easier. There’s no mess and no need to use expensive chemicals, knives or power tools in order to remove what you don’t want.
All you do is simply submerge your model in water for a couple of hours (up to 24 for bigger prints). The PVA dissolves away completely, leaving you with sharp, clean lines on the overhanging areas of the object that you’ve created.
Warm water can speed up the process. Some more complicated prints may take longer.
Using a soluble support material like PVA requires that you use a printer with dual (or more) extruders. One extruder handles the support material, the other handles the main printing filament.
If you’re not currently using a dual extruder printer, it’s very likely that you can easily upgrade in order to get the increased flexibility and creativity that multiple extruder printing offers.
For example, two extruders not only allow you to use support materials, they also allow you to print in more than one color.
Now that you know what PVA is and how it is used, let’s take a look at some of its features:
- It is water soluble, biodegradable and non-toxic;
- It has a high tensile strength and is also quite flexible;
- It is odorless when used in printing;
- It easily adheres to other substances;
- It resists oil, grease and solvents;
- PVA will begin to partially hydrolyze (breakdown) at a temperature of 180C;
- Therefore, PVA filament temperature for printing is between 190C and 210C;
- PVA tends to work better with PLA than ABS, since the higher printing temperatures that ABS requires sometimes means that PVA will have trouble adhering.
PVA isn’t the only soluble support filament available for use in 3d printing. There are other soluble support filaments, such as HIPS, that essentially do the same thing as PVA. As a result, it’s useful to look at a comparison of PVA vs. HIPS to understand the pros and cons of both materials.
This Moai has nothing to do with PVA, the print didn't even need supports. We just thought it sitting in a glass of water might give you an idea what watching your PVA dissolve might look like. Enjoy.
To begin with, PVA is not only water soluble, it is also hygroscopic. This means that it naturally absorbs water from the air that surrounds it. This makes PVA extremely sensitive to humidity.
If PVA is exposed to air that contains too much water it will begin to lose its tensile strength and degrade. Therefore, it is always important to store PVA in an airtight container, perhaps one containing a desiccant, especially if you live in a climate that experiences high humidity on a regular basis.
HIPS does not have this problem, since it is neither water soluble nor hygroscopic. However, HIPS’ non-water solubility gives rise to another problem – removing it as a support medium once you’re finished printing.
Unlike PVA, you can’t simply chuck a HIPS model in water. Instead, in order to remove HIPS you have to use Limonene, a chemical solvent. Unlike water, Limonene isn’t odorless. So, using HIPS can be, potentially, more irritating than using PVA.
In the end, it comes down to a matter of preference. PVA requires more careful storage than HIPS, but is water soluble. HIPS is easily stored, but requires a chemical solvent to remove. If you don’t mind taking the steps to protect PVA in storage then it probably provides an easier soluble support solution than HIPS.
How to print with PVA:
Like all 3d printing materials, knowing the specific PVA filament properties will make your print as successful as possible. First, you want to keep your fan speed a bit on the low side since PVA can be fragile while extruding.
Next, set the temperature of your bed to between 50C and 60C, maybe a tad hotter for the first few passes. This will help with adhesion. We also recommend a printing temperature of between 190C and 210C, depending on your extruder.
Regarding the best PVA filament settings; you want to keep your printing speed slower than normal, somewhere around 30mm/sec. If you go faster than that you run the risk of the material not lying properly.
This is what happens when PVA overheats. Make sure you've got those cooling fans on!
The balancing point with finding the best PVA filament temperature (or the sweet spot where it prints nicely) is that you don't print any hotter than you absolutely need to. Depending on what you're printing (if there aren't many overhangs or bridges) if the support material extruder is left hot for a while in between printing, it can clog up the extruder.
A lot of the problems that people experience when printing with PVA comes from using an inferior product. PVA that contains impurities and additives can cause inconsistent melting which, in turn, can cause blobbing, irregular flow and clogged extruders.
All of these problems mean that you have to spend more time trying to get your printing job done right. In addition, you also have to use more PVA. Your time is money. The PVA you use to print costs money.
When you use a high quality PVA you avoid all of the above problems. You save time, you save money and you eliminate the frustration of watching a carefully planned print go down the drain.
Here's a sample of our PVA Filament 1.75mm - also now available in 2.85mm or 3.00mm
Our PVA is the highest quality available. Its translucent color demonstrates that it is pure polyvinyl alcohol, with absolutely no additives or contaminants. We also manufacture our PVA to super-tight tolerances of just +/-0.03mm either side of the diameter you purchase.
All of this means that when you use our PVA filament 3mm or 2.85mm, you save time and money and get a successful print run - time after time.