I need more info on what exactly you are welding and what welding process these rods are used with.
If these rods are for arc welding (SMAW) then, you are better off with MIG (GMAW) welding the aluminum.
If these are used for Oxy-fuel welding then, if you are experienced enough with this type of welding, your welds should come out just fine if for instance, you're welding and aluminum motorcycle gas tank with the proper torch, tip, flame setting, and technique.
The question you are asking cannot be answered completely because, you need to provide all of the necessary information in order to give you the appropriate advice. What I mean by this is that you need to let me know what type(anodized), grade(1000,2000,4000,5000,6000 series), thickness,
joint design, etc. Then and only then, can I or anybody else, answer your question, and give you the correct advice. No offense!
Please let me and everyone else know what your application consists of.
Regards,
SSBN 727 Run Silent. Run Deep!!!