A 75 ml glass bottle of liquid masking medium from the Daler-Rowney Watercolour Mediums range. The fluid is a pale cream that dries to a soft rubbery skin, and the label carries the name in five languages — Gomme Réserve, Maskierflüssigkeit, Líquido de Escaramiento, Medium Mascherante Liquido — because it is the same product wherever watercolour is taught.

It exists to solve the one problem watercolour cannot solve on its own. There is no white paint in transparent watercolour that reads as bright as the paper itself, so the white has to be planned and protected before any colour goes down. Masking fluid is what protects it: paint it over the sails, the highlight in an eye, the spray off a wave, the whitewash on a village wall, then wash freely straight across the top.

Removal is a fingertip job. Let the wash dry completely — properly dry, not almost — then rub the mask gently with a clean dry finger or a rubber cement pickup and it rolls off as a skin. Rushing it while the paper is even slightly damp is what tears the surface, and that damage cannot be repaired afterwards.

Two habits protect your brushes and your paper. Never apply it with a good sable, because the latex sets in the ferrule and finishes the brush; use an old synthetic, a ruling pen, a colour shaper or a cocktail stick, and wet the bristles with soapy water first so the fluid rinses out. And test a corner of the paper before committing, because soft or thin sheets lift their surface when the mask is pulled.

In Pakistani summer heat this is a bottle to store with some care. Masking fluid thickens, then goes stringy, then finally turns to rubber in the bottle, and heat pushes it along that road far faster than time does. Keep the cap tight, keep the bottle out of direct sun and out of a hot cupboard, and stir it gently rather than shaking it — shaking whips in bubbles that dry as pinholes in the mask.

The label carries its own safety text and it is worth reading before use: it lists the contents as including natural rubber, warns that the product is irritating and may cause respiratory allergies, and notes that exposure may cause an allergic reaction. Anyone with a known latex allergy should not handle it.

The Safencia price is Rs. 2,300 for the 75 ml bottle. Cash on Delivery is available across Pakistan, and stock, your city and delivery charges are confirmed on WhatsApp before dispatch.

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