Many of my LPs have old yellowed paper inner sleeves, or sleeves that have printing on them (e.g. lyrics). I'd like to preserve them but store the records in something else. I also want to preserve what's left of the outsides of my albums.
Are polypropylene or polyethylene inner and outer sleeves safe to use, or are there better and safer materials? An example of the polypro and polyethylene bags I'm talking about are these outers and these inner sleeves from Sleeve City. There are also some paper sleeves of various kinds on the inner-sleeve page. Are these preferred over the poly sleeves, or is it the other way around?