Paraformaldehyde and formaldehyde solution both deliver the same reactive molecule, formaldehyde, but in very different forms. One is a free-flowing solid, the other a water-based liquid. Choosing the right one can simplify your process, cut freight costs and improve product quality. Here is how they compare.
What is paraformaldehyde?
Paraformaldehyde (often shortened to PFA or “para”) is a solid polymer of formaldehyde. It is made by concentrating formaldehyde solution until the formaldehyde molecules link together into short chains. The result is a white solid that typically contains 91{39499548087bf5d6456720590ab548a06fd15c0472d9a38a1fcaa1e4add42826} to 96{39499548087bf5d6456720590ab548a06fd15c0472d9a38a1fcaa1e4add42826} formaldehyde, with the balance mostly bound water. It is supplied as a fine powder or as free-flowing, low-dust prills.
When paraformaldehyde is heated, or dissolved in the presence of a small amount of acid or base, the chains break down and release formaldehyde again, ready to react.
What is formaldehyde solution?
Formaldehyde solution (formalin) is formaldehyde dissolved in water, usually at 37{39499548087bf5d6456720590ab548a06fd15c0472d9a38a1fcaa1e4add42826} to 50{39499548087bf5d6456720590ab548a06fd15c0472d9a38a1fcaa1e4add42826} strength, with a little methanol added as a stabiliser. Because it is already a liquid, it can be pumped straight into a reactor, which makes it the default choice for large, continuous plants.
Key differences
| Property | Paraformaldehyde | Formaldehyde solution |
|---|---|---|
| Physical form | Solid: powder or prills | Liquid |
| Formaldehyde content | About 91–96{39499548087bf5d6456720590ab548a06fd15c0472d9a38a1fcaa1e4add42826} | About 37–50{39499548087bf5d6456720590ab548a06fd15c0472d9a38a1fcaa1e4add42826} |
| Water brought into the process | Very little | Around half or more of the weight |
| Formaldehyde per tonne shipped | Roughly 2 to 2.5 times more | Lower |
| Typical packaging | 25 kg bags, bulk bags | Tankers, drums, IBCs |
| Storage | Dry, cool, sealed | Tanks, often temperature-controlled |
| Dosing | Must depolymerise (heat, catalyst) to react | Pumped directly |
When paraformaldehyde is the better choice
- Water-sensitive reactions. Many organic syntheses, and resins that need high solids content, work better without the large amount of water that comes with formaldehyde solution.
- Long distances from the producer. Because it carries far more formaldehyde per tonne, paraformaldehyde can be much cheaper to ship, especially for export markets.
- Batch and smaller-volume users. Bags are easy to store and dose by weight without tanks or pumps.
- Agrochemicals and pharmaceuticals. Paraformaldehyde is used in the manufacture of crop-protection chemicals and pharmaceutical intermediates, where controlled, low-water formaldehyde is valuable.
- Disinfection and fumigation. Gently heating paraformaldehyde releases formaldehyde gas in a controlled way.
When formaldehyde solution is the better choice
- Large, continuous resin plants located near the supplier, where tanker delivery and pumping are simplest.
- Processes that tolerate water, such as many standard UF, MF and PF resin recipes.
- Lowest cost per kilogram of formaldehyde at high, steady volumes close to the source.
Storage and handling tips
Keep paraformaldehyde in its sealed packaging in a cool, dry, well-ventilated area, away from heat, acids and alkalis. Moisture and heat can cause caking and the slow release of formaldehyde gas. Formaldehyde solution should be stored in suitable tanks at the temperature recommended for its grade, so that paraformaldehyde does not precipitate. Both products are hazardous: use appropriate personal protective equipment and always follow the Safety Data Sheet.
Paraformaldehyde and Formaldehyde from META4
META4 Hydro Carbons manufactures both products. Our Paraformaldehyde is available as prills or powder with an assay of 91{39499548087bf5d6456720590ab548a06fd15c0472d9a38a1fcaa1e4add42826} to 96{39499548087bf5d6456720590ab548a06fd15c0472d9a38a1fcaa1e4add42826}, packed in 25 kg bags and super sacks, with capacity of 20,000 MTPA. Our Formaldehyde is available in concentrations from 37{39499548087bf5d6456720590ab548a06fd15c0472d9a38a1fcaa1e4add42826} to 50{39499548087bf5d6456720590ab548a06fd15c0472d9a38a1fcaa1e4add42826} in bulk, drums and IBCs.
Not sure which form suits your process? Contact our team and we will help you compare the options for your application.