입자가 불균하게 성장하고 잔류 유리상이 남아 있어 광학적 등방성이 감소하여 투과도가 감소된 것으로 추정된다.
It really is assumed that the transmittance is decreased because of the non-uniform growth of the particles and the rest of the glass phase, which decreases the optical isotropy.