I have a 13.7 mb ai file I need to email (from my iMac) to a a few screen printing companies. Their minimum file sizes are 10 and 12 mb.
Can anyone recommend a good app for me to use to reduce or compress this file?
I do not see why you cannot contact the screen printing companies to see if they have a form or repo you can submit your files to. If the printer is only taking email source files then that is an issue in itself. Some printers do have a minimum but what I've seen is around 2gb in size so I don't know if that is the issue you're facing. I would look into submitting a PDF but all this depends on the requirements of the screen printer.
After reading the comments I would suggest consulting with the designer about submitting a Printer PDF with the printer's specs. If you're having issues request the designer to consult with the printer. I do not see why that would be an issue but that depends on your relation with the designer and the designer's experience with the printing process.
In the end if this too much of a hassle you should contemplate is it really worth the setup fee VS the time invested to try to avoid it? Also, similar to embroidery, if you do pay a setup fee you can typically request the files they converted so that might be a route to take if you plan on using another printer so ask your printer on what their policy is.