Hello, can be used together in the same formula.
Retinal (Retinaldehyde) must be blended to dissolve the oil in the formula. By using heat to help dissolve, but
Encapsulated Retinol is directly soluble in water. and should avoid heat in mixing, it is recommended to separate
Encapsulated Retinol in the last step. When the cream is creamy, then gradually add. and blended together