White silkies are usually recessive white. Red sex links (isa browns) are usually red columbian with a single copy of dominant white. I’m going to assume that your white silkie has partridge or black under the recessive white, which is most common, but certainly not the only two possibilities. If that’s the case and he has partridge under his white, you’ll get white chicks with red leakage, black chicks with red leakage, and/or possibly a messy partridge pattern either in black or white. If he has black under the recessive white, you’ll get white chicks with minimal black spots, black chicks, black chicks with red leakage, white chicks with some red leakage, and/or white chicks with minimal black spots and some red leakage.
If he doesn’t have partridge or black under his white, or it’s dominant white instead, the results will be completely different. However, expect some white/mostly white chicks and ones with red leakage/patterning.
