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I'll get a little technical here. Shellac is a thermo plastic coating. Essentially it forms a film by solvent evaporation which is alcohol, and forms a monolithic film. It does not form pinholes in the film like oils and acrylics. That's why it is an effective barrier to control odor especially nicotine. Thermoplastic coatings are dissolvable in their own solvent. Shellac can be re-wet by wiping alcohol on the surface. Thermosetting coatings cannot be re-dissolved in their own Solvent. Unless the system is exposed to a high pH and is not PH tolerable The spelling is incorrect because I'm using Siri. However what happens sometimes is when a primer is applied to a drywall surface the solvents can release odors that are embedded in the drywall. In the case of shellac once the solvent has evaporated the film is inert monolithic and completely sealed. What may have happened is the alcohol in the shellac has softened the nicotine and is creating a lingering odor. Or the system was supplied too thick and the solvent is unable to escape completely. You may be able to allow the residual solvents to escape by wiping with denatured alcohol. As a general rule of thumb if there is a nicotine contamination that is severe it is best to hand wash with trisodium phosphate and rinse with clean water and then apply the shellac. Paint odors are a challenging complaint for homeowners because everyone has a different sensitivity to odor. They may be used to the odors in the house and now you have changed the environment and acclamation. Any residual odor is not harmful and sometimes boxes of baking soda will absorb air born odors. Trisodium phosphate is an excellent cleaner however it leaves a slimy residue if not rinsed thoroughly and can compromise adhesion.
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