How do I remove grease or oil from unfinished wood before staining?

Short answer

To remove grease or oil from unfinished wood before staining, draw out as much contamination as possible with an absorbent (baking soda, whiting, or cornstarch), then clean with a solvent wipe (mineral spirits or naphtha). Follow with a mild degreaser wash, let the wood dry thoroughly, and sand lightly (120–180 grit) to restore an even surface. Repeat until a solvent “preview” shows no dark, blotchy areas. If faint residue persists, spot-seal with a thin coat of dewaxed shellac before staining.

Why this works

Oil and grease penetrate wood fibers and block stain from soaking in evenly. Absorbents pull oils back to the surface, solvents dissolve and carry them away, and a detergent wash breaks remaining films. Drying and sanding re-open the grain for uniform stain absorption. The goal is a clean, dry, freshly abraded surface that takes stain consistently.

Tools and materials

• Absorbent: baking soda, cornstarch, whiting powder (calcium carbonate), or unscented clay kitty litter (crushed)
• Solvent: mineral spirits or naphtha (naphtha evaporates faster)
• Mild degreaser: wood-safe cleaner (e.g., Krud Kutter Original) or dish soap solution
• Clean white cotton rags and paper towels (lint-free)
• Plastic scraper or putty knife
• Nylon brush or soft scrub pad
• Random orbit sander (5 in.) with 120, 150/180 grit discs
• Shop vac with brush attachment and tack cloth or microfiber
• Optional: dewaxed shellac (e.g., Zinsser SealCoat), gel stain if spot-sealing
• PPE: nitrile gloves, eye protection, organic vapor respirator, good ventilation

Step-by-step

1. Assess and prep

   • Brush off dust and debris. Identify fresh vs. old stains. Fresh grease looks wet; older stains appear dark and dry. A quick wipe with solvent should wet evenly—any spots that stay dark likely still have oil.

2. Draw out the oil

   • Sprinkle a generous layer of baking soda/cornstarch/whiting over the stain. For deeper stains, make a poultice: mix absorbent with enough mineral spirits or naphtha to form a thick paste. Spread 1/8–1/4 in. thick, cover loosely with plastic to slow evaporation, and leave 1–8 hours.
   • Scrape off the paste with a plastic scraper and discard. Repeat if the absorbent darkens significantly.

3. Solvent wipe

   • Dampen a clean white rag with mineral spirits or naphtha (do not soak). Wipe with the grain, flipping to clean sections often to avoid smearing oil back into the wood. Follow with a dry rag to pick up residue.

4. Degrease wash

   • Use a wood-safe degreaser, or a mild dish soap solution. Agitate lightly with a nylon brush along the grain, then wipe with a damp cloth.

   Dish soap solution: ~1 tsp dish soap per 1 quart (0.95 L) warm water
   Rinse: clean water, well-wrung cloth
   Dry time: 12–24 hours with good airflow

1. Dry thoroughly

   • Let the piece dry until it feels room-temp dry and shows no cool or damp feel to the touch. A moisture meter should read close to baseline for your shop (typically 6–10% indoors) before sanding.

2. Sand and inspect

   • Sand lightly: 120 to level raised grain, then 150–180 for most hardwoods. Vacuum and wipe with a clean microfiber.
   • Do a “solvent preview”: wipe a small area with mineral spirits. If you see darker halos or uneven wetting, repeat steps 2–4.

3. Optional spot-seal

   • If a faint stain remains that you cannot remove without over-sanding, seal just that area (or the whole surface for uniformity) with a thin coat of dewaxed shellac (1–2 lb cut). Scuff sand with 220 after drying, then use a gel stain or a compatible dye/stain system.

Tips for best results

• Naphtha flashes faster than mineral spirits, which helps limit grain swelling. It’s great for oily fingerprints on hardwoods.
• Whiting powder (calcium carbonate) or Fuller's earth outperforms baking soda on stubborn spots and is inexpensive.
• For softwoods (pine, fir), apply a pre-stain wood conditioner after cleaning and sanding to reduce blotching.
• Always test your stain on a hidden area or scrap from the same project after cleaning.

Common mistakes to avoid

• Over-wetting bare wood. Excess water can raise grain and cause swelling; use well-wrung cloths and let the surface dry fully.
• Skipping the absorbent step. Solvents alone can spread oil rather than remove it.
• Sanding too fine before staining. Grits over 220 can burnish the surface and reduce stain uptake, especially on maple and birch.
• Using silicone-based cleaners or lubricants anywhere near wood you plan to finish. Silicone causes fish-eye defects that are hard to fix.
• Leaving solvent-soaked rags in a pile.
  • Dispose of rags safely: lay flat to dry outdoors, store submerged in water in a sealed metal container, or follow local hazardous waste guidelines.

Time and cost

• Materials: $10–$40 (absorbent, solvent, degreaser, sandpaper). Shellac, if needed: $20–$30/quart.
• Labor: 1–3 hours of active work plus drying time. Deep, old stains may require a full day with repeats.

When to call a pro

• Antique or high-value pieces where aggressive cleaning or sanding could reduce value.
• Old workbenches/countertops saturated with oil, where planing or chemical stripping may be required.
• Suspected silicone contamination (from polishes) that keeps causing fish-eyes—refinishers have silicone removers and specialized sealers.

Quick checklist before staining

• Surface is clean, dry, and sanded to 150–180 grit.
• Solvent preview shows even wetting with no dark halos.
• Dust removed with vacuum and clean cloth.
• Apply conditioner or shellac only if needed and compatible with your stain choice.

Handle the cleaning patiently and methodically, and your stain will lay down evenly with rich, predictable color.