The first important thing to understand is that once baseball cards have stuck together, you will likely never separate them perfectly without causing some damage. Therefore, the goal should be minimizing further damage rather than futilely trying to pry them apart perfectly. Sticking occurs due to the paper breaking down over time from environmental factors like humidity, heat, light exposure, etc. and becoming sticky. This often happens along the edges and corners first before spreading.

To start, examine the stack of stuck cards carefully without moving them yet. Look for any cards that are not as stuck and may be separable without assistance. Gently try sliding a few of these out to the side as practice test cards. You want to do this part very slowly and carefully to avoid forcing and tearing the paper fibers. Set these aside for later inspection.

For the bulk of the stuck stack, you need to rehydrate the paper fibers to make them supple enough to separate gently rather than tear. Place the stack card-side down directly into a shallow baking pan or other non-metallic container. Slowly add just enough distilled or boiled (cooled) water to come about halfway up the side of the stack without soaking the tops of the cards. You can also use a humidifying tray or container. Let this sit undisturbed for 12-24 hours to allow thorough wetting.

After the soak time, check the water level and top it off if needed, then let sit for another 6-12 hours. The goal is to hydrate fully without risk of warping from over-soaking. Gradually wicking water in allows it to penetrate deeply and evenly. At this stage, don’t even attempt separation yet – more soak time is needed.

You want the paper to be pliable but not soggy when you start to separate them. Give the stack a total soak time of 48-72 hours, checking and topping off the water every 12 hours or so, before proceeding. Quick or uneven soaking can cause tearing or creasing. With patience you minimize risk of further damage.

When the soak is complete, gently slide the saturated stack out of the water container card-side up onto a dry, non-abrasive surface like a clean towel or blanket. Starting from the top, use your fingernails positioned along the edge to try sliding a card away from the stack in a single slow, constant motion without jerking or stopping.

Go very gradually and don’t force it if resistance is met, to avoid tearing. Have dry paper towels handy. As cards separate, wipe and blot them dry one by one before laying them flat aside to dry fully. The goal is to dry them before re-sticking occurs as the paper fibers re-solidify. Slight nicks or creases may form despite care – this is better than shredding whole sections by forcing separation. Repeat for each card, soaking, sliding and drying one at a time from top to bottom.

As cards are removed, keep rotating the process so lower layers have time exposed at the top to soak further before attempting separation. Some tiny paper particles may come off in the water or on card surfaces – these can be carefully wiped away after full drying is complete to avoid detracting from card condition down the line.

Monitor for mold growth during long soak times – add a teaspoon of white vinegar to the water as a preservative if needed. Once fully dry with no residual wet stickiness, use protective sleeves for storage to prevent recurrence of sticking issues in the future. Handle carefully from here on out to preserve condition. With patience, the process allows stuck cards to be successfully separated while minimizing further damage to the fragile paper. Collection care requires diligence.