Could these sleeves be made solid instead of sheer?

Yes, the sleeves can be made with 2 layers of chiffon, but it will be still a little bit see through. By adding a satin lining underneath the chiffon, it’s not see-through at all. Both are makable, you could leave a note with your order in the comment or special requirement box how you prefer the sleeves to be, and we'll see it and make it that way :)