Can the patch be thin enough to wear under makeup?

Short answer: yes, and the limit is not thickness — it is edge behaviour. A thin patch disappears under foundation only if the edge is tapered and the matrix does not swell sideways as it absorbs. A patch that is thin but blunt-edged will show a ridge within an hour, whatever the caliper says.

What "thin enough" actually means

Two numbers get confused. Total caliper is what buyers quote; the number the wearer experiences is how far the edge stands off the skin after ten minutes of movement. A 0.3 mm sheet with a hard cut edge reads thicker than a 0.45 mm sheet with a tapered edge, because the taper lets the outline follow the skin instead of cutting a step into it.

So the specification to ask for is a pair: caliper plus edge treatment. Quoting one without the other is where most "under makeup" claims fall apart in the first sampling round.

Three things that decide whether it disappears

The daytime and overnight split

Thin and highly absorbent are competing properties. A patch thin enough to vanish under makeup holds less fluid, so it is the wrong choice for a large, still-active spot overnight. The practical answer most brands end up with is two SKUs: a thin tapered daytime patch, and a thicker one for sleep — and packaging that makes the difference obvious rather than leaving the buyer to guess.

This is also why we ask what the patch is for before quoting a caliper. "As thin as possible" produces a product that looks invisible in a photo and lifts in the first hour of wear.

Testing it before you commit

A sample can only tell you so much. Ask for the patch to be worn under foundation for a full day, on a moving area — jawline or cheek, not the back of a hand. Look at three moments: immediately after application, after four hours, and after removal, when you can see whether the edge has left a ring or taken surface cells with it.

If the trial fails, the fix is usually edge geometry or uptake, not a thinner sheet. Cutting caliper further tends to trade a visible ridge for an early lift.