For more information, look for Destry Kenning's article, "Dealing with the Reactivity of Aluminum Forms and Concrete" in the Summer 2018 edition of Concrete Facts magazine. It's part 1 of a 4-part series so stay tuned for more!
Are you seeing veins or worm-like trails on your concrete panels? There's a reason for that. The elemental aluminum present in the aluminum forms is very reactive with the cementitious materials in concrete. Chemical reactions are much stronger than physical reactions and the results are concrete buildup. Additionally, hydrogen gas creates bubbles on the concrete surfaces. As these bubbles migrate upward, they leave these unsightly trails on your panels.
There are ways to prevent these problems. You can try a resinous coating on the aluminum form surface, but there are pros and cons to a heavy coating and a thin coating. Another option is to react the aluminum with something in advance to prevent or minimize further reaction when it comes into contact with the concrete. This process is known as "seasoning". Read the article to see what Kenning has to say about various seasoning methods!