A peelable coating that’s meant to protect a PCBA for years and one that’s meant to mask a part through a single sandblasting pass both peel off cleanly when the job is done — but treating them as the same product means specifying a disposable process mask for a job that needed a genuine functional conformal coating, or the reverse. Incure’s Pyra-Sil™ peelable silicone line covers both jobs across four one-part grades, split by whether the coating is meant to stay on or come off on purpose almost immediately.
891 and 906 Are Functional Conformal Coatings, Not Temporary Masks
Pyra-Sil™ 891 is a room-temperature-cure, self-leveling coating built for sealing, potting, seam-filling, and encapsulation — genuine conformal-coating jobs, not disposable masking. It cures tack-free in 8 minutes and fully cures in 24 hours at 25°C, covering a wide -45°C to 260°C service range at a thin, self-leveling 800–1,200 cP viscosity. Pyra-Sil™ 906 takes a different path to the same functional-coating role: a low-viscosity 200–300 cP formulation that heat-cures in just 20 minutes at 130°C rather than relying on ambient cure, built specifically as a tough, durable PCBA coating over a -65°C to 200°C range. Both fluoresce under blacklight for coverage inspection and both peel cleanly from metals and plastics if rework is ever needed — the peelability is a rework convenience on these two grades, not the primary reason they exist. Both are also compatible with manual brushing and high-volume automated dispensing, so the choice between them comes down to service temperature and cure equipment rather than application method: 891’s broader -45°C to 260°C range and ambient cure suit a line without oven capacity, while 906’s tighter -65°C to 200°C range and fast 130°C bake suit a line that already has one and wants the shorter cycle time.
894 and 899 Are Disposable Process Masks, Split by Viscosity
Pyra-Sil™ 894 and 899 exist for a genuinely different job: temporary protection during sandblasting, machining, and plating operations, where the coating’s entire purpose is to come off cleanly once the process step is finished. Both are one-part, self-leveling, moisture-cure coatings with a pot life under 8 minutes, tack-free in 15 minutes, and a full cure of 72 hours at room temperature — a slower full cure than 891’s despite a similar initial tack-free window, reflecting that these two grades are optimized for masking durability through a process step rather than fast turnaround to final cure. The two differ by viscosity and hardness: 894 runs 35,000–45,000 cP at Shore A15–A25, while 899 is noticeably thicker at 65,000–95,000 cP and harder at Shore A25–A35 — the thicker, harder 899 is the more resilient choice for more aggressive abrasive processes, while 894’s lighter consistency suits finer surface detail where a heavier mask might obscure features that need to stay accessible. Both share 891’s same -45°C to 260°C service range, though their tensile strength runs lower at 120 PSI against 891’s 220 PSI — a reminder that it’s worth confirming spec numbers directly rather than assuming a “temporary” masking product simply inherits the functional coatings’ full mechanical profile. Where they don’t give anything up is weathering, moisture, and UV resistance: 894 and 899 hold up against the same environmental exposure the permanent grades resist, they’re just formulated to release cleanly rather than stay bonded indefinitely.
Email Us with your substrate, whether the coating needs to stay on the part or come off after one process step, and your cure-time window, and Incure’s engineers can confirm which Pyra-Sil™ grade actually fits.
Cure Speed and Temperature Range Reflect How Each Grade Is Actually Used
891’s 24-hour full cure at room temperature suits a production line that can hold parts overnight without an oven step. 894 and 899 both stretch to 72 hours despite a comparably fast initial tack-free window, a schedule that works because a masking coating just needs to be tack-free and durable enough to survive the process step — reaching full cure on the slower end doesn’t hold up the line the way it would on a functional coating headed straight into service. 906 breaks from all three with a 20-minute heat cure at 130°C, the fastest path to full cure in the line by a wide margin, at the cost of requiring oven capacity the other three grades don’t need. Matching that cure profile to actual line throughput and equipment availability is as much a selection factor here as viscosity or hardness.
Where the Line Fits
PCB and electronic assembly protection favors 891 or 906 depending on whether room-temperature or accelerated oven cure fits the production line better, with 906’s tougher, lower-viscosity formulation suited to boards headed into harsher field service. Sandblasting, machining, and plating operations that need a removable mask rather than a permanent coating draw on 894 or 899, chosen by how abrasive the process step actually is. Facilities running Incure’s UV conformal coating line for permanent PCB protection can add Pyra-Sil™ specifically where a coating needs to come back off — either for rework on a functional coating or as a disposable process mask that was never meant to stay.
Contact Our Team to confirm the Pyra-Sil™ grade for your process and substrate.
Visit www.incurelab.com for more information.