The wrong amount of heat can leave brown or yellow scorch marks on your light-colored or synthetic substrates, destroying an otherwise quality print. You can prevent scorch marks on your final products by carefully applying heat to your screen prints; that means proper setup, monitoring and quality control to keep your screen prints looking sharp.
To prevent scorching, you need to adjust the way you apply heat to your screen prints. But first, it helps to know which substrates are likely to scorch. Light-colored garments, particularly white or light heather gray, are prone to showing scorch marks. Lighter-weight cottons also scorch more easily. Many synthetic fabrics simply won’t tolerate heat, and they’ll scorch more easily than their cotton counterparts.
Many screen printers run every screen print through the conveyor dryer in the exact same way. To prevent scorching on easily marred fabrics, you need to adjust the heat and speed settings on your conveyor dryer. Fabrics that are more likely to scorch should be run through the conveyor dryer at a lower temperature for a longer period of time.
For more on this subject, read Getting the Most out of Your Conveyor Dryer to Cure Challenging Garments
Flash cure units can be another culprit when it comes to scorching fabrics. The temperature of the flash cure unit should be lowered when dealing with fabrics that are likely to scorch. The height of the unit also should be raised so the substrate is farther from pallet while the ink is being flash cured.
For more, check out A General Guide to Quartz Flash Cure Settings
Some situations call for specialty ink to prevent scorching. When synthetic fabrics or light-colored fabrics can scorch if run through the conveyor dryer at the temperature and speed required to cure regular plastisol ink, you might need to use specialty ink that cures at a lower temperature.
Many conveyor dryers and flash cure units are equipped with temperature controls so that you can carefully dial in on your ideal curing temperature. While those controls are great for customizing your machine for each print job, to prevent scorching and ensure thorough curing, you should be monitoring the temperature of your conveyor dryer and flash cure unit during your print projects. The longer a unit runs, the hotter the temperatures in the dryer or under the flash cure will be. The temperatures also might vary based on the temperature or humidity within your print shop. Monitoring the temperatures of garments with a temperature gun, specialty tape or a probe can help you spot spikes in equipment temperatures that could result in scorching.
Read Smart Strategies for Measuring Curing Temperature for more helpful info
If garments do suffer scorch marks under the flash cure unit or in the conveyor dryer, you don’t necessarily have to toss them on the damage pile. Extremely white garments often can have the scorch marks removed, saving the garments. You can run them through the washing machine to see if the scorch marks come clean, or you can spray down the scorch marks with a commercial solution intended for the job or with a mix of hydrogen peroxide and water.
Nearly every screen printing shop deals with scorched garments from time to time. By knowing which garments are likely to scorch and how to reduce the risk of scorching, you can lessen the occurrence of scorched garments in your screen printing shop. And when garments do scorch, you might be able to salvage them and reduce the waste in your shop.