Soluble support is chosen by compatibility, not by quality. Both of these dissolve in plain water, both print through an ordinary hotend, and both will be ruined by a fortnight on an open shelf. What separates them is the temperature the other nozzle is running at.
The short answer: PVA for PLA, BVOH for PETG and nylon. The longer answer explains why, and why the shelf life matters more than either.
The temperature ceiling that decides it
PVA prints at 190–220 °C, and its stored weakness list names the constraint directly: it degrades in the nozzle when printed alongside anything above about 230 °C. That is not a limit on PVA's own nozzle — it is a limit on the chamber and the idle time, because a PVA nozzle sitting hot while the other material prints at 250 °C will cook its contents into a carbonised plug.
BVOH's window is 200–225 °C and it is markedly more thermally stable, which is the reason it exists. That stability is what lets it partner materials in the 240–265 °C band.
So the pairing table falls out of the base material:
- PLA, at 195–225 °C — PVA, comfortably.
- PETG, at 230–250 °C — BVOH. PVA is marginal at best here.
- Nylon, at 250–280 °C — BVOH, and even then expect to manage the idle temperature carefully.
- ABS, at 230–260 °C — neither, usually. HIPS and limonene is the established pairing, as ABS against HIPS sets out.
What the support costs per print
Isolate the soluble portion of a dual-material job and cost it on its own:
- 28 g of support and purge tower.
- 3 of the print's hours attributable to it, on a machine drawing 100 W.
- Machine overhead of 50 cents an hour, and power billed at the German household rate of 41 US cents a unit — a deliberately expensive market, to show that even there the energy is not what decides this.
- One job in ten scrapped, since a support failure takes the part with it.
In PVA at $95/kg, the middle of its $60–130 range: $4.76, of which $2.66 is filament and 12 cents electricity. In BVOH at $120/kg, the middle of its $80–160 range: $5.54, with $3.36 of filament.
Under a dollar per print between them, and the electricity is the same 12 cents either way. At 28 g of support the choice between them is noise; at ten times that mass, on a plate of tall overhanging parts, it is not. The mass field in the cost calculator is the one that tells you which of those two situations you are actually in.
That is a small difference and it is not where the money goes. The money goes into spools that die on the shelf, which is the next section and the important one.
Shelf life is the real cost of both
These materials dissolve in water. That is the product. It also means they absorb water from the air more aggressively than anything else on this site, and the stored note for PVA is unambiguous: an unsealed spool is ruined within days.
A ruined spool is not a spool that prints slightly worse. It is one that has swollen, gone tacky, jammed the extruder and become impossible to feed. At $95 or $120 per kilogram, losing one to a fortnight on a bench is a much larger cost than the difference between the two materials.
The rules that follow are simple and non-negotiable:
- Back in the sealed container the same day, every time, with fresh indicating desiccant.
- Dry before use, PVA at 45 °C for 6 to 12 hours and BVOH at 50 °C for the same, and check for weight loss rather than assuming.
- Print from a dry box for anything long. These are the materials where a dried spool goes wet during the print.
- Buy small spools. A 500 g reel you finish is worth more than a kilogram you half-use.
Storing filament so it stays printable covers the containers; these two are the reason that page exists.
Dissolving them
Both go into plain water. Warm water dissolves faster than cold, and gentle agitation — a small aquarium pump, or simply changing the water — makes a large difference, because the dissolved layer otherwise sits against the support and slows everything down.
Thick support columns take hours. Thin interface layers take minutes. This is a design lever: support that is planned to be thin dissolves in a fraction of the time of support that was allowed to grow solid.
Do not pour the resulting solution into a septic system in quantity, and do not put it down a drain you care about; a saturated polyvinyl alcohol solution is viscous and it will find the narrowest part of your plumbing.
What each one is like to print with
Beyond the temperature window, the handling differs in ways that show up on the first print.
PVA is the softer and stickier of the two. It grips the base material well — sometimes better than you want at the interface — and it is prone to oozing, so the purge tower and the wipe settings do real work. It also prefers a modest bed at 50–60 °C and behaves like PLA on the plate.
BVOH is stiffer and feeds more reliably, with a bed range extending to 70 °C to suit the hotter partners it is bought for. Its stored strength range of 25–45 MPa against PVA's 20–40 is not a property you care about in a support material, but it does translate into a filament that snaps less often on the reel.
Both are best printed slowly, and both benefit from an enclosure, which their stored requirement lists as helpful rather than necessary — mostly because the partner material usually wants one anyway.
Which to buy
If you print PLA and nothing else, PVA and the saving are correct.
If you print PETG, nylon, or a mixture, buy BVOH. The thermal window is not a nicety — a soluble filament that degrades in the nozzle produces a jam mid-print and takes the part with it, which costs far more than the price difference.
And if you are only occasionally printing geometry that needs soluble support, buy the small spool of BVOH. Its wider compatibility means one reel covers everything, and one reel used up is cheaper than two reels gone off.