Water-based paint knowledge base-Wood bumps


Wood bumps - Common problems with water paint

Wood grain is exposed when broken or damaged wood comes into contact with water.A good example of this is when a curved toothpick is placed in water, it will draw water through the capillaries, elongate, and straighten.When the fibers on the board are exposed, they suck water into the wood like a straw, causing the fibers to swell and stick to the surface.

Woodiness processing is having main effect to grain protuberance. Plywood made with a blunt saw blade has more damaged wood fibers and has a "fuzzy" feel to the surface.Hardwoods with pipe holes often have wood ridges in the wooden pipe-holes . Red oak usually has triangular wood grain protuberance sometimes, wood fiber two ends join in board surface, and among protuberance, form an inverted "V" wood grain protuberance.Such ridges are very difficult to remove.Sanding is merely a temporary flattening of the wood fibers.When the next layer of water-based paint is applied to the wood surface, the wood fibers will resurface.A more effective method is to use a hard brush or wire brush to remove wood fibers or pipe holes before painting.

Although ridges are almost impossible to remove, we can add some steps to the recipe to reduce the occurrence of ridges.One way is to use a saturated coating. A typical saturated coating is a transparent coating of 3-4% adhesive solids.A typical saturated coating is a transparent coating of 3-4% adhesive solids.On the wood substrate, apply the saturated coating between any coating added.The effect of saturated coating is to cause grain process, and wood grain coagulation, so that wood grain in the saturated coating drying can not relax.Next, gently polish to remove the worst grain. Scotchbrite, by Scotchbrite, is the preferred tool for this type of sanding because it is not good for breaking more wood.

A quick-drying coating can also help reduce ridges.A quick film-forming or water-based coating that removes water quickly can limit water intrusion into the wood fibers, thereby reducing the ridges.Sinograce Chemical of Special resin polymer for Acrylic Industrial coatings PF - 136 with a small particle size, good permeability, quick drying, etc, especially suitable for closed application of timber, effectively prevent because of the wood fiber water swelling and shrinkage problem.In addition, azeotropic solvents such as ethanol and isopropanol help to remove water from the coating. If such a method is used, care must be taken not to increase the formation of microbubbles while shortening the drying time.

Additives that limit the flow of water and prevent it from entering the substrate will naturally reduce ridges. Compared with other thickeners, alginate, CMC and HEC really thicken the water, rather than reacting with polymers and pigments, and have no effect on thickening the continuous phase of the coating.

Finally, the best way to prevent ridges is to use a hybrid system, which is a combination of water-based and solvent based coatings.If the first coating applied to the wood is solvent based, it can effectively seal the wood and prevent future water-based coating from causing ridges.

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