I have personally had an example of needing to add boric acid to a MgAl comp to prevent a reaction. The comp I used it in was pyrotex' s sodium nitrate glitter. I had a reaction which caused the stars to crumble into dust, I traced the issue to the charcoal which I picked (oak) which turned out to have an extremely high ph. I added boric acid to the next batch and the issue went away.
This may not be a typical use of this combo of chems but it may be the reasoning behind its appearance in many comps. Many charcoal tend to become quite basic and the acid is likely added as a preventative measure, (just a theory).
Ok an update, I've found the new formula in question. Independence white strobe star: KNO3-52.4, MgAl-20, BaNO3-9.5, sulfur-8.6, Boric acid-4.7, dextrin-4.8
This formula does not support my theory of charcoal PH balance due to the lack of charcoal so there must be some other reason for its use.
Edited by NeighborJ, 17 October 2017 - 10:03 AM.