The liquid in pastry is a compromise you make on purpose

Everything below about liquid in pastry dough comes from what actually happens rather than from what is supposed to.

The two things water is doing

Water hydrates the flour proteins so they can link into gluten, which is what holds the sheet together while you roll it. That same gluten toughens the baked pastry, so more water means a stronger, chewier and less tender result.

A dough with too little water crumbles apart on the bench and cracks as it is lifted into a tin. A dough with too much rolls beautifully and bakes into something closer to a biscuit tin lid. The whole craft of pastry making sits in finding the least water that will still make a workable sheet.

Why quantities in recipes are approximate

Flours differ in how much water they absorb, and the same brand varies between batches and seasons. Humidity in the kitchen changes both the flour and how quickly the surface dries as you work. The fat you used also contributes liquid, and butter carries considerably more water than a vegetable shortening does.

By the second rise, this is why recipes say to add water gradually rather than tipping in a measured amount at once. Judging the dough rather than the jug is the only reliable method, however precise the recipe looks.

Adding it without overshooting

Sprinkle the liquid across the surface of the rubbed mixture rather than pouring it into one spot. Cut it through with a knife or a scraper instead of a hand, since fingers warm the fat and encourage kneading.

Stop when the mixture holds together if pressed, even though it still looks too dry in the bowl. Resting the dough allows the water present to spread evenly, and what looked dry usually becomes cohesive. Adding more water to a dough that simply had not rested is the most common way pastry gets toughened.

What cold water is for

Cold liquid keeps the fat firm, which matters for flakiness and for how the dough handles under a rolling pin. Warm water softens the fat immediately and pushes the pastry towards short and greasy rather than layered. Ice in the measuring jug is a simple insurance, as long as the ice itself does not go into the dough.

In a warm kitchen chilling the flour as well as the water buys useful minutes of working time.

None of this matters much for a pressed oil-based base, where there is no solid fat to protect.

Egg, cream and other liquids

Egg yolk brings fat and emulsifiers with its water, so it adds richness and tenderness alongside binding. Egg white is mostly water and protein, and it firms the pastry rather than softening it. Cream and soured cream add fat and a little acid, both of which weaken gluten and produce a more tender crust.

Each of these binds with less gluten development than plain water for the same volume of liquid. They also add flavour and colour, which is why sweet pastries so often use yolks rather than water alone.

Proving times are written for a warm kitchen, and yours may not be one.

The alcohol question

Replacing part of the water with a spirit or with vodka is a well-known trick for a more tender crust. The reasoning is that alcohol wets the flour and makes the dough workable without hydrating protein the way water does. Much of the alcohol evaporates during baking, taking with it liquid that would otherwise have left gluten behind.

In the tin, the effect is real but modest, and it will not rescue a dough that was overworked in the first place. Treat it as a small margin of safety rather than a licence to handle the pastry more roughly.

The takeaway

Add the least liquid that will hold the dough together, then rest it before deciding you need more.

Patience is an ingredient, and it is the one people leave out.