Epoxy Etching from Alkaline Solution

I have client that uses the light from a LED with a clear epoxy end and a phototransistor, housed in a similar clear epoxy package, to measure the clarity of a soap solution. He is worried that in time the clear surfaces of the devices will become cloudy during years of being immersed in a strong soap solution. He wants to conduct a year-long test, to determine if the solution etches the epoxy. Couldn't a stronger hot alkaline solution, such as potassium hydroxide, be used to accelerate his testing? Do you think his concerns are justified? What other materials would be better than epoxy?

David A. Johnson, P.E. --- Consulting Engineer