A kiss is an additional ball contact that changes the intended result, often when the cue ball meets the first object ball again. It may spoil a route, redirect it or alter the final position. Find the actual contact before changing your stroke.
Two lines on paper are not enough
Ball centres do not need to follow intersecting lines for the balls to touch: each ball has width. Conversely, two drawn paths can cross safely when the balls pass at different times. Think of occupied space at the same instant, not an intersection alone.
Follow all three balls. The first object ball may return from a cushion, block the cue ball or move the second target. Do not assume a fixed tangent departure for the object ball. The cited collision research studies spin and friction effects; it is not a calibration or a guaranteed recipe for this training layout.
Locate the failure before choosing a correction
Replay from the first contact and identify which pair meets, where it happens and whether it is before or after the intended point. A cue ball arriving short without any extra contact is a different problem. If a collision already changed the route, do not diagnose the final miss as an aiming-system error alone.
Separate three cases in your notes: the first ball obstructs the return; it moves the final target; or the paths pass close without touching. Include the arrival order and remaining speed. Watching only the cue ball can make these cases look alike.
Test one change, then check the whole route
Open the actual practice preset below and choose a candidate first object ball and route. Record aim, speed and spin, run it once, then return to the same starting layout. Compare a modest speed change with aim and spin held fixed. Record contact pair, place, sequence of cushion contacts and whether the second target is reached legally.
More speed changes both balls' travel and can also change rebound behaviour; it does not automatically remove a kiss. If speed alone gives no repeatable clearance, separately test a different cut or route and recheck all contacts. Do not change speed, aim and spin together and then claim to know which fixed the problem. Repeat on the physical table before treating a simulated clearance as reliable.
A useful contact still has to meet the rules
A planned redirection is not automatically a valid point. Under the cited UMB three-cushion rule, the cue ball needs at least three cushion contacts before contacting the second object ball; other foul restrictions still apply. A late cushion cannot repair an early second-object contact. A collision after a point may change continuation without being the cause of a missed point.
The preset is an editable starting position, not a certified solution or proof that every stroke from it will kiss. Keep the successful route and the failed comparison together. The useful outcome is an observed difference you can explain, not a promised success rate after a few sessions.
Try the actual kiss-risk position
This card uses the app’s saved coordinates and opens the same three-ball layout. Choose and record the stroke yourself; the diagram does not draw an unverified winning path.
Kiss risk
White 120 × 71 cm · Yellow 150 × 81 cm · Red 240 × 40 cm
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