It is the question people are too polite to ask and the one they are most quietly worried about, particularly in a room they did not furnish. The answer is no, and the reason it is no is worth understanding.
The question comes up in about a third of first bookings, usually obliquely, usually phrased as something else. It deserves a direct answer. The gel does not stain. It is clear, it carries no dye and no pigment, and it is water-soluble, which means that whatever it touches can be returned to its previous state with water alone. There is no oil in it, and oil is the thing that marks fabric permanently.
That is the chemistry. The practical answer is a little longer, because staining is not really what people are asking about. What they are asking is whether a room is going to be left in a state that has to be explained to anyone.
Nothing is opened until the sheet is down. It is not a token layer; it is a full waterproof sheet that goes over the bed linen and is covered in turn with towels, and it is laid before the gel is even taken out of the bag. Everything that happens in the session happens on that surface. Gel does not travel the way oil travels — it is thick and heavy and it stays more or less where it is put, so the spread is contained to the working area rather than wicking outward through the bedding.
The sheet, the towels and the gel all arrive together and all leave together. The therapist carries her own, which is the only sensible arrangement for outcall work; asking a room to supply what a technique needs is how rooms end up damaged.
The session ends under the shower, which is not a courtesy at the end but part of the technique. The gel rinses off skin completely with warm water and no soap is strictly needed for it, although most people use some. What goes down the drain is water and a dissolved seaweed sugar.
The used towels and the waterproof sheet are gathered and taken away. The bed underneath is remade. In an ordinary session the room afterwards looks like a room in which two people had a drink, and the only trace is that it is warmer than it was.
The two places worth mentioning honestly. Gel on a tiled bathroom floor is genuinely slippery and stays slippery until it is rinsed, which is why the bathroom gets a towel down and a rinse after, and why the walk from bed to shower is taken at a sensible speed. That is the only real hazard in the technique and it is entirely manageable by anyone paying attention.
Carpet is the other. Gel on carpet does not stain it, but it does need water and blotting rather than wiping, and the honest preventative is not to get there — hence the sheet, hence the towel line, hence the fact that the pouring happens on the bed and not standing up. In practice, with the preparation done properly, this does not come up.
The reason this question goes unanswered on most pages that sell the technique is that answering it requires admitting the technique is messy, and messy is not a word marketing likes. It is messy. It involves a litre of warm liquid and two bodies, and pretending otherwise would be silly. The point is that it is messy inside a boundary that is set up in advance and cleared afterwards, and that boundary is a five-minute job done by someone who has done it several hundred times.
If the room itself is the worry rather than the linen — a rented apartment, a hotel with thin walls, a bathroom the size of a cupboard — that is a fair thing to raise when you book. It changes nothing about the rate, which is set out in full on the prices page, and it occasionally changes which therapist comes, because some are better at small rooms than others.