Printing on white aluminum. Printing initially revealed tons of scratches, adhesive marks from protective layer, and cloth marks from cleaning with our starting solution (simple green, denatured alcohol, tap water). We switched to cleaning with mineral spirits and it took everything out perfectly. The only new problem is that there are some oil spots it can leave behind that are impossible to see until after you’ve printed on it, which, of course, means the whole print has to be discarded. Best substrate cleaning/prep practices for clean printing? How can I avoid these issues in the future? Thanks!