How Are Water Soluble Sachets Made? The Manufacturing Process Explained

Drop a water soluble sachet into water and it’s gone within seconds. The film dissolves, the concentrated formula inside disperses and nothing is left behind. It’s a simple experience for the customer using it, but what goes into producing that sachet is a more involved process than you might expect. This blog walks through how water soluble sachets are made, from the chemistry inside to the film that wraps it and everything in between.

What a Water Soluble Sachet Is and What It Isn’t

Before getting into how they’re made, it’s worth being clear about what a water soluble sachet is, because the term is sometimes misunderstood.

The sachet is the primary packaging, the wrapper that’s in direct contact with the formula inside. It dissolves completely when it touches water, leaving minimal residue behind which is significantly better than traditional plastic packaging.

There is, however, outer packaging that holds the sachets during storage and transport. This is typically cardboard, designed to be recycled at the end of its use so the reduction in waste comes from two places: the sachet dissolving at the point of use and the outer packaging being recyclable rather than single-use plastic.

Stage 1. Formula Development

The process starts well before any film or sachet is involved. The formula that goes inside the sachet has to be developed and tested first and this is where the most significant work happens.

Water soluble sachets work by removing water from a chemical formula. Most conventional liquid cleaning products are largely water by volume. That water adds weight, increases the amount of packaging needed and contributes nothing to how the product performs. A concentrated formula strips that water out and packages only the active ingredients.

What’s important to understand is that this isn’t as simple as just reducing an existing liquid product down. The formula has to be completely redeveloped to work as a stable concentrate that dilutes correctly when the sachet dissolves. There are also real limits to what a water soluble sachet can hold and not every type of chemical can be adapted into this format and testing compatibility between the formula and the film is a non-negotiable step. Solupak’s bespoke solutions process begins here, with in-house chemists developing formulas that match each client’s specific requirements.

Stage 2. PVA Film and What It’s Made From

The film that forms the sachet is made from polyvinyl alcohol, usually shortened to PVA or PVOH.

To produce the film, PVA resin is mixed with a set of additives that determine how the film behaves. These control things like how quickly it dissolves, what water temperature is needed to trigger that dissolution, how tough it is during filling and sealing and how well it protects the contents in storage. Once the blend is ready, it’s cast into thin, even sheets and dried. The result is a clear, flexible film with a consistent thickness throughout.

Stage 3. Film Conversion

Once the film is made to the right specification, it’s cut and shaped into the sachet format needed for that particular product. This is called the conversion stage.

The size and shape of the sachet are decided by a few things: how much formula it needs to hold, how it will be used, how the end user will dispense it and whether the formula inside is liquid or powder. Liquid concentrates need a format that seals cleanly around liquid. Powders need a shape that keeps the dry material well away from the seal area during closing. The end result of this stage is an open sachet, the right size and shape, ready to be filled.

Stage 4. Filling the Sachet

Filling is where the concentrated formula goes in and accuracy is the priority. The whole point of a pre-dosed water soluble product is that every sachet contains the right amount, every time. If the fill weight varies, the pre-dosing benefit disappears.

For liquid formulas, the filling equipment measures out an exact volume into each sachet. For powders, it works to a precise target weight. Both methods are checked and recalibrated throughout the production run to keep things consistent. Filling also happens under controlled conditions to prevent any contamination of the film around the seal area. Solupak’s water soluble manufacturing facility runs at a capacity of 80,000 sachets per shift, using bespoke machinery built specifically for this type of production.

Stage 5. Sealing

Once the sachet is filled, it’s sealed using heat. The PVA film responds to heat and pressure to form a bond that completely closes the sachet. That seal needs to be strong enough to keep the contents secure through storage and handling, while the film itself still needs to dissolve cleanly and fully once it hits water.
The heat settings, including temperature and how long the heat is applied, are set during the development phase and kept consistent throughout the production run. A poor seal can mean a sachet that fails in transit or storage, which depending on the formula involved can be a safety issue, not just a quality one.

Stage 6. Quality Testing

Nothing leaves the production line without passing quality checks. For water soluble sachets, that means testing seal integrity, fill weight accuracy, dissolution performance and formula stability.

Seal integrity testing checks the sachet will hold its contents through whatever it encounters in storage and transit. Fill weight checks confirm the dosing is consistent across the run. Dissolution testing confirms the film and seal break down within the right timeframe under real conditions. For sachets containing regulated formulas, sector-specific testing is also carried out before production is signed off. Where clients need documented results for compliance or procurement, Solupak’s ISO-accredited manufacturing operation is set up provide them with that.

Water Soluble Sachet Manufacturing at Scale

Solupak has been manufacturing water soluble sachets since 1998, with machinery and facilities built specifically for this type of production rather than adapted from a general packaging line. The current capacity is 80,000 sachets per shift, which gives the production scale to support high-volume clients across a wide range of sectors at the same time.

Those sectors include facilities management, catering, construction, agriculture, healthcare, dental, optical and large retail operators. Each has its own formula requirements, its own standards around how sachets need to dissolve and its own compliance considerations.

When Bespoke Water Soluble Manufacturing Is the Right Route

Not every client arrives with a finished formula ready to go. Many come with a performance requirement, such as a cleaning result they need to achieve, a dosing specification, or an industry standard to meet and need the formula and the sachet developed together from scratch. That’s the bespoke route and it’s where Solupak’s in-house chemistry capability makes the biggest difference.

The process starts by understanding exactly what the product needs to do: in what setting, at what dilution and how the end user will use it. Formula development and film selection then happen in parallel, with compatibility testing confirming everything works together before production begins. The finished sachet is designed for that specific application from the inside out, not adapted from something that already exists.

Making water soluble sachets to a consistent standard at commercial volumes requires every stage of the process to be controlled and connected. At Solupak, that whole sequence happens in-house, which removes the handoffs and inconsistencies that come from using multiple suppliers across different stages of production.

To discuss your water soluble sachet manufacturing requirements, whether you’re starting from an existing formula or a performance brief that still needs developing, get in touch with our team today.