Clean Seal envelopes are great for all of your mailing needs. These are great for sending promotional materials, small catalogs or important documents. Self-sealing envelopes are made from white wove paper for durability. Form a secure seal quickly, with no moisture required. Open-end design. White envelopes are made of crisp white woven material for a substantial feel. Simply peel off the release strip and press Self-sealing envelopes are made from white wove paper for durability. Form a secure seal quickly, with no moisture required. Open-end design. White envelopes are made of crisp white woven material for a substantial feel.