[Peter_Spaeth]

I found this online.

For cards, I think that there are three variations of this, and pressing in general is not accepted.

(1) Soaking - this is usually fairly common especially in prewar cards where you usually soak the card in water to remove it from a scrapbook, etc. It is also sometimes used to remove excess dirt or other residue that has accumulated on the card. After the water soak, the card is usually dried and then placed under some heavy objects such as books to ensure that it dries flat. This process may also remove some warping in the card. I believe this is usually acceptable in the card community as long as NO CHEMICALS ARE USED. Only water or distilled water is acceptable. Anything else is considered altering the card.

(2) Pressing - this is the process to remove wrinkles or creases in the card. This is not acceptable as sometimes over time, the wrinkles or creases may come back. A card may look to be crease-free when it is originally submitted to a TPG. However, at a later time, the creases re-appear, and observers wonder how such a card with creases got such as high grade and got past the graders.

(3) Pressing to trim - one of the reasons that there is a minimum size requirements to cards is to prevent unscrupulous sellers from trimming a card with soft corners so that the end product is a card with sharp corners. They then submit this card for a grade, but it will often fail due to minimum size requirement. However, one way to get around this is to press the card so strongly that the size of the card increases (but it becomes thinner). Then the card is trimmed, so that the corners are now sharp and it is still within the minimum size requirements. Obviously, this is not acceptable to the collecting community. >>

The pressing(#2 above) aspect reminds me of what many did in the 80's/90's with a process called "spooning". Where one rolled a spoon,the bottom/curved part of the part of the spoon that holds the liquid, back/forth over a crease/bubble to flatten it. Also the pressing to trim(#3 above) was accomplished via pressing a card under a certain tonage (PSI) in a mechanical press of sorts to "stretch" the cardboard thereby allowing more material to be trimmed from the edges. This does in fact result in a thinner stock card.