Compatibility of resins. Importance of the light source

When selecting resin from a different manufacturer than the 3D printer, it's important to consider its compatibility. The compatibility of a resin is established based on two parameters: the wavelength for which it has been optimized and the technology for which it has been formulated.

Compatibility according to the wavelength of the light source

3D printing resins use photoinitiators to activate polymerization through light. There are different types of photoinitiators optimized for different wavelengths, so compatibility must exist between the photoinitiator (and therefore the resin) and the printer's light source.

Image 1: Visible light spectrum. Source: Wikipedia.

In the market, resins optimized for three wavelengths can be found: 365 nm, 385 nm, and 405 nm, with those at 405 nm or compatible with all three wavelengths being the most common. Therefore, special attention should be paid when choosing resin if you have a printer with a light source at 365 nm or 385 nm. This does not mean that it's not possible to use resin optimized for a different wavelength than that of the printer, but its performance will be much lower and will require much longer exposure times.

It is advisable to always select resin optimized for the wavelength of the printer being used, in order to achieve the best results with shorter exposure times.

Likewise, consideration must be given when selecting a curing device that includes lamps with the appropriate wavelength.

Compatibility according to technology

In general, it is common to find two groups of resins depending on the compatible technology: SLA and LED/DLP. It is not recommended to use resins developed for LED/DLP in SLA printers or vice versa, as they usually have different reactivity. Although some resins may work well in other technologies, it cannot be guaranteed, and in some cases it will be impossible.

Image 2: SLA vs DLP vs MSLA. Source: theorthocosmos.

The incompatibility of resins is not usually a common problem because currently formulations compatible only with 365 nm and 385 nm or optimized for SLA are minority.