signbrad
New Member
This is almost surely an issue with the plastic rather than the vinyl or the application method.
Not all polycarbonates are the same. There are many grades and formulations among the manufacturers. Even within the Lexan brand family (owned and manufactured by Sabic, a Saudi Arabian company), there are a number of different formulations with various additives and characteristics. Sabic even makes a plant-based polycarbonate, as does Mitsubishi, among others.
Polycarbonate absorbs moisture and must be dried/cured before processing. A typical recommended drying temperature is 250 degrees. Is that the temperature you dry your Lexan?
Polycarbonate also re-absorbs moisture, and under the right conditions (high heat and moisture) some of its physical characteristics can be significantly compromised.
Is there a foolproof way to know that you are using the best polycarbonate for your end use? I doubt it. Traditionally, this industry (signs) has relied on trial-and-error to make decisions on materials. When we find something that works, we tend to stick to it. But how do you know three years in advance that something will fail? Or how do you know when a manufacturer changes a formulation, or when a supplier makes a substitution?
This is one of the arguments against using polycarbonate. For large signs, I have always preferred a flexible face, anyway. For small signs, acrylic doesn't yellow and is easier to machine. To avoid acrylic blowouts, I have always relied on hanging bars. Breakage? If I were worried about breakage, I wouldn't have glass windows in my house. In a sign, I generally consider breakage a non-issue. But I will use polycarbonate by request. I rarely volunteer it, though.
Brad in Kansas City
Not all polycarbonates are the same. There are many grades and formulations among the manufacturers. Even within the Lexan brand family (owned and manufactured by Sabic, a Saudi Arabian company), there are a number of different formulations with various additives and characteristics. Sabic even makes a plant-based polycarbonate, as does Mitsubishi, among others.
Polycarbonate absorbs moisture and must be dried/cured before processing. A typical recommended drying temperature is 250 degrees. Is that the temperature you dry your Lexan?
Polycarbonate also re-absorbs moisture, and under the right conditions (high heat and moisture) some of its physical characteristics can be significantly compromised.
Is there a foolproof way to know that you are using the best polycarbonate for your end use? I doubt it. Traditionally, this industry (signs) has relied on trial-and-error to make decisions on materials. When we find something that works, we tend to stick to it. But how do you know three years in advance that something will fail? Or how do you know when a manufacturer changes a formulation, or when a supplier makes a substitution?
This is one of the arguments against using polycarbonate. For large signs, I have always preferred a flexible face, anyway. For small signs, acrylic doesn't yellow and is easier to machine. To avoid acrylic blowouts, I have always relied on hanging bars. Breakage? If I were worried about breakage, I wouldn't have glass windows in my house.
In a sign, I generally consider breakage a non-issue. But I will use polycarbonate by request. I rarely volunteer it, though.Brad in Kansas City
