Difference between chrome and vegetable tanned leather

Here are the main difference between chrome tanned and vegetable tanned leather:

Chrome tanned leather	Vegetable tanned leather
1. The Leather is slightly elastic.	1.Less elastic than chrome tanned leather
2. Less affected by acidic atmosphere.	2. Affected by acidic atmosphere
3. Difficult to wet back.	3. No difficult to wet back
4. Absorb fats slowly.	4. Absorbs more fat than the chrome tanned leathers very quickly.
5. Stands the boil test.	5. Does not stand the boil test.
6. Cannot be dyed with basic dyes.	6. Cannot be dyed with direct dyes.
7. Fibres try to come out from the cut portion.	7. Fibres do not come out from the cut portion.
8. Very good embossing is difficult.	8. Embossing expressions are excellent and permanent.
9.Tries to become loose if proper precautions are not taken.	9. Looseness is less than chrome tanned leather.

Uses of organic acids/ Masking agent in Chrome tanning

Masking agent: 

There are some chemicals mostly organic acids and their salts which when added to basic chrome sulphate liquors, will raise precipitation point, buffer the solution and reduce tanning affinity of the chrome. The organic acids or their salt which bring sucha changes are called masking agent.
Masking agent changes any on all of the following properties-

• The composition of Cr compound
• The pH of Cr liquor
• The electrical migration of Cr compound
• The ability of the liquor to resist precipitation

Organic acids used for masking - 

• Formic
• Acetic
• Oxalic
• Adipic
• Succinic acid etc.

N.B: Effective  masking agent - Na adipate, Na ptalate.

Advantages of masking agent: 

Masking agent has the following advantages- 
1. The pickling of the pelt can be very light or sometimes may be omitted.

• Reduce Harsh grain
• Reduce acid swelling
• Reduce hardness

2. Tannage is quicker

3. Tannage is straight forward and no adjustment of basicity is necessary

4. Considerable saving in the amount of Cr2O3 needed for satisfactory tannage, better exhaustion of tan-bath.

5.Productin of leather of higher Cr2O3 content.