Old furniture shows cracking and crazing for a number of reasons, some environmental, some chemical. Alligatoring or crazing is one of the signs that a piece may be antique, or rustic and hand-crafted with incompatible available finish materials. It's fairly simple to re-create the effect with contemporary faux painting kits, or with something as basic as school glue. Salvage a boring "save" from the attic, or reinvent a flea market find with a faux web of cracked paint that looks like the real thing.
Crackle Kit Control
A faux-aging crackle kit provides crackle medium, applicators and clear instructions for creating a fine or prominent web of crazing on painted surfaces. You decide exactly where to place the "deteriorated" paint by limiting the areas you cover with the glazing medium. The thickness of the application can also be manipulated to achieve a spidery fine web or strongly defined cracks in the topcoat. Since authentic crazing represents paint that has broken due to weathering or the disintegration of age and then collected dirt in the cracks, it's usual to paint the base coat in a darker color and the topcoat a lighter shade so the cracks will show clearly. Paint the piece, let it dry hard -- overnight is good -- sponge or brush on crackle glaze where you want the effect to show, and apply the topcoat when the glaze is just tacky. The chemical reaction of the paint and glaze does the rest. Protect the finish with a clear, nonyellowing polyurethane or varnish.
Spray and Craze
All-over crackling with spray-on crackle paint may save you a step, but it doesn't work quite as well for isolating specific areas than it does for crackling the entire piece. Follow the directions of the manufacturer -- several well-known and widely available paint suppliers make crackle spray paint -- and be sure to use water-based latex for your topcoat for best results. Select a base coat color that contrasts with the topcoat; the base coat is all-in-one color and crackle glaze medium. Spray two coats of the color, typically a darker shade, on a surface cleaned of dust and dirt so the paint will adhere. The instructions may say to wait only two to three minutes between base coats. When the base coats dry to tacky, spray on a contrasting topcoat and watch the crackling take over as the topcoat dries. Experiment with two light base coats and one even topcoat for light crackling; two heavy base coats and two or three layers of topcoat for medium cracks; or two heavy base coats and three or four even topcoats for large crackling.
Create a "cheap" antique with supplies you have around the house. Leftover paint and school glue will transform old furniture into faux-aged furniture, a degree of difference that imparts a touch of class. Paint the surface of the piece with a dark latex or acrylic and let it dry. Brush a generous coat of white school glue over the dry paint; the direction of your brushstrokes determines the orientation of the eventual cracks. Brush in the direction of the grain for cracks that run along the grain of the wood. As soon as the glue sets -- it can still be tacky or just barely dry but not hard -- paint the contrasting topcoat over the piece and leave it. Glue takes longer than commercial crackle medium to craze the topcoat, but it will create cracks along the application strokes that give you an almost-instant faux-antique. Spray-on clear finish will help to keep your crackled effect intact, and you won't risk dissolving the glue and smearing the crackling, as you might with a wetter brush-on finish.