Where does orange peel collide?

In coatings, orange peel is a finish defect: the dried paint film is covered in shallow bumps and dimples that resemble the skin of an orange, rather than flowing out flat. It arises when the wet film fails to level before it sets: from spray droplets that do not merge, too-fast solvent loss, high viscosity, or poor atomization. Wicks and colleagues' Organic coatings: Science and technology explains the leveling and surface-tension balance that decides whether brush or spray marks flow out or freeze in as orange peel. The referent is a surface-texture defect graded by gloss and distinctness of image, not a skin sign or a metal roughening.[1]

Unit

Severity of surface undulation in the cured film

Recovery means

Orange peel is corrected by sanding smooth and recoating with adjusted viscosity, solvent, or application

Measured by

Rated by visual standards and by gloss and distinctness-of-image meters that quantify surface waviness

In clinical medicine, peau d'orange ("orange-peel skin") is a physical sign: the skin takes on a dimpled, pitted look because fluid builds up in the dermis while the hair follicles stay tethered, pulling the surface into pits like an orange rind. It is a classic finding in inflammatory breast cancer and in lymphedema, though, as Weedon's 1998 Peau d'orange of the breast cautions, it does not always signal advanced cancer. The referent is a visible skin texture read as a diagnostic clue, distinct from a paint defect or a metallurgical surface despite the identical orange-skin metaphor.[2]

Unit

Presence and extent of dermal dimpling over the affected skin

Recovery means

The sign recedes if the underlying edema or disease causing it is treated

Measured by

Identified on clinical examination of the skin and corroborated by imaging and biopsy of the cause

In metal forming, orange peel is a roughened, pebbly surface that appears on sheet metal after it is stretched or deep-drawn when the metal's grains are coarse. Each large grain deforms slightly differently, so the free surface ends up undulating at the scale of the grains, marring the finish of the formed part. Ikeno's 1953 On the orange peel at deep drawing of 2S sheet studied the defect in aluminium sheet and tied it to grain size. The referent is a forming-induced surface roughness controlled by grain size, unrelated to a paint finish or a skin sign.[3]

Unit

Surface roughness developed on strained sheet relative to grain size

Recovery means

Avoided by using fine-grained stock; a formed orange-peeled surface is remedied by finishing operations

Measured by

Quantified by surface roughness after straining and correlated with the metal's grain size