Leather is a porous material, which means that ink can seep into its surface quickly. The sooner you address the stain, the easier it will be to remove.

There are two main types of leather:

1. Finished Leather:

Treated with a protective coating, making it less absorbent.

2. Unfinished Leather (Aniline):

 More porous and delicate, requiring extra care during cleaning. 

- Test First:

Always test cleaning methods on a small, inconspicuous area of the couch to ensure they don’t damage or discolor the leather.

- Avoid Harsh Chemicals:

 Products like bleach or abrasive cleaners can ruin leather.

- Work Gently:

Excessive scrubbing can strip the leather of its natural oils and finish. 

To remove pen marks from a leather couch, gather the following items:

- Mild soap (like dish soap)

- Soft cloths or cotton balls

- Isopropyl alcohol (rubbing alcohol)

- Leather cleaner or conditioner

- White vinegar (optional)

- Nail polish remover (acetone-free, optional)

- Baking soda (optional)

- Water 

1. Start with Mild Soap and Water

This method works for fresh or light ink stains:

1. Mix a few drops of mild soap with warm water.

2. Dampen a soft cloth in the soapy solution and wring it out to avoid soaking the leather.

3. Gently rub the pen mark in a circular motion.

4. Wipe away any soap residue with a clean, damp cloth.

5. Pat dry with a soft towel.

If this doesn’t work, proceed to the next method.

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2. Use Rubbing Alcohol

Rubbing alcohol is effective at breaking down ink without being overly harsh on leather:

1. Dampen a cotton ball or soft cloth with rubbing alcohol.

2. Blot the ink stain gently, avoiding rubbing, as this could spread the ink.

3. Replace the cotton ball as it absorbs the ink, and repeat until the stain fades.

4. Clean the area with a damp cloth to remove alcohol residue.

5. Apply a leather conditioner to restore moisture and shine.

Note: Avoid over-saturating the leather with alcohol, as it can dry out the material.

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3. Try White Vinegar

White vinegar is a natural and gentle cleaner:

1. Mix equal parts white vinegar and water in a bowl.

2. Dip a soft cloth into the solution and wring out the excess liquid.

3. Dab the stain gently, being careful not to rub.

4. Wipe the area with a damp cloth and dry it with a towel.

5. Apply a leather conditioner to restore the leather’s natural oils.

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4. Use Acetone-Free Nail Polish Remover

For stubborn ink stains, acetone-free nail polish remover can be a good option:

1. Apply a small amount of nail polish remover to a cotton ball.

2. Blot the stain gently, working in small sections.

3. Once the ink begins to lift, wipe the area with a damp cloth to remove residue.

4. Dry the spot and apply a leather conditioner.

Warning: Test this method in an inconspicuous area first, as nail polish remover can strip the finish from some leather types.

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5. Baking Soda for Absorption

For dried or older pen marks, baking soda can help absorb ink:

1. Sprinkle baking soda over the stain.

2. Dampen a soft cloth and rub the baking soda into the stain using circular motions.

3. Let it sit for a few minutes, then wipe away the residue with a damp cloth.

4. Dry and condition the leather.

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6. Use a Leather Cleaner

Commercial leather cleaners are formulated to tackle tough stains while preserving the leather:

1. Follow the instructions on the leather cleaner.

2. Apply it to the stain with a soft cloth or applicator.

3. Wipe off any excess product and buff the area with a clean cloth. 

After removing the pen mark, it’s important to maintain the leather’s condition:

1. Apply Leather Conditioner:

Restores moisture and flexibility to the leather, preventing cracks or dryness.

2. Buff the Surface:

Use a dry, soft cloth to polish the area for a uniform finish.

3. Protect the Leather:

Consider applying a leather protector to guard against future stains. 

- Keep Pens Away:

Avoid leaving pens near the couch, especially if children are around.

- Use Throws or Covers:

Protect high-use areas with removable covers.

- Clean Regularly:

Wipe down your couch weekly to remove dirt and prevent stains from settling.

- Apply a Leather Protector:

A protective coating can reduce the leather’s absorbency, making it easier to clean spills and stains. 

If the pen mark persists despite your efforts or if the stain has deeply penetrated the leather, it’s best to consult a professional upholsterer or leather specialist. They have the tools and expertise to safely remove stubborn stains without damaging your couch.