How to Handle Screen Printing Emulsion Problems: Freezing & Freeze-Thaw Emulsion
Screen printers are constantly troubleshooting their screen printing supplies, including how to handle freezing and freeze-thawed emulsion problems. Getting a shipment of screen printing emulsion can be stressful during the winter, especially for shops in the colder parts of the country because certain emulsions are ruined if they freeze. The various types of emulsions - Diazo, Dual-Cure, Photopolymer, Capillary and Films - all have different freeze-thaw properties. Some are able to go through the freeze-thaw transition safely, while other screen printing emulsions are ruined.
It is important to note that during winter shipments, your emulsion might become frozen at some point on its shipping journey. Every screen printer should know that there is also a distinction between fully frozen and partially frozen. Just like the name suggests, fully frozen emulsion is solid (or has frozen) all the way through. Partially frozen screen print emulsion is typically only frozen on the top or part of the way through the bucket.
How to Recognize Emulsion That Is No Good After Being Frozen
It is important to be able to visually recognize emulsion that is no longer good and usable once it freezes and thaws. There are 3 key points to realizing you might have frozen emulsion problems.
1. Emulsion that is not freeze-thaw safe will look grainy. While a screen printer might try to still use this emulsion, the tiny particles cause adhesion issues and will have problems cross-linking to your mesh. A good way to test this yourself is to coat one side of your frame and expose it. If you have issues, then the emulsion went bad because of freezing.
2. Look for a “layered” effect in the emulsion. Stir the emulsion from the bottom and let it drip from your spatula back into the bucket. You are looking for a creamy “pancake batter” consistency. If you see tiny particles, it looks grainy or is clumpy and not flowing smoothly, you might have an issue. After mixing, let the emulsion sit for a few hours. Screen printing emulsion that is not freeze-thaw stable will separate again.
3. The emulsion will be “gelled” and maybe form into various sized rubber balls inside the container. These rubberized emulsion balls will be hard to break apart.
How to Tell if Your Diazo Sensitizer for Dual Cure and Diazo Emulsions is Bad
Dual cure and diazo screen printing emulsions still suffer from freeze and thaw issues, but the diazo sensitizer is not known for suffering from freezing issues. In fact, major manufacturers of emulsion, including Ulano, are known to keep their emulsion sensitizers in freezers prior to shipping to extend the shelf-life.
On very rare instances, you might see your diazo go from a powder to solid. This could be an indicator of freezing and a problem with the sensitizer. If this happens, call your supplier as it is very rare.
Handle Emulsion Freezing Issues When Ordering Screen Printing Supplies
Knowing how to handle freeze-thaw emulsion issues will lead to smarter ordering of screen printing supplies. When placing an order for emulsion, try to avoid shipping over the weekend if the weather is freezing. Stock up on Freeze-Thaw safe emulsion and other silk screen printing supplies now with free shipping.