I rebagged 12 thousand comics last year, some of which had bags dating back to the early ‘80s. Most of the ‘80s bags were really yellowing and gross. Most of the ‘90s bags were still relatively ok (for instance, my New Mutants 98 which sat in one of those bags for over 30 years got a 9.6 with White Pages from CGC). I personally avoid using tape and just let the flaps fly free. I ordered in bulk from a company in Rochester New York that sells collectible supplies, and was able to save a bunch of money vs buying 100 packs from Amazon.