A textured wall will need more paint than a smooth wall. The texture adds more surface area, even though it doesn't increase square footage. Determining the additional surface area depends on how much texture there is. Painters will probably estimate about 300 to 350 additional square feet of paint to account for texture. Factor additional surface area into your square footage calculations when seeking professional estimates.
If you plan to hire a professional painter (plus crew), you should expect to shell out a few hundred dollars for the average 10×12 room. Depending on your area, this could exclude the price of certain materials. So for a four bedroom house, getting each bedroom painted + the cost of larger common areas (if you’re going for a full repaint) can really add up.
Modern Masters 1 gal. Brass Metallic Interior Paint Modern Masters 1 gal. Brass Metallic Interior Paint can be used to create a high-end decorative finish in a variety of circumstances. Use it on a small accent piece or large architectural specification. Durable and long lasting for commercial application yet easy enough for do-it-yourself projects. Special formula contains real ...  More + Product Details Close

Back to the article. You can add water to all latex based paints / thinner to oil based paint. The tinting base has absolutely nothing to do with it. Say you are working outside and throughout the day you have to add a little water to keep the same consistency. If somebody really tried to add 20% to 50% water they no longer would be painting they'd be performing a whitewash or pickle finish.

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