1821
This may be a surrounding material that protects these surfaces or they may be residual material due to inconsistencies in the process , similar to flash in moulding operations .
 material: be; material: material; concept or principle: surfaces; material: be; material: material; concept or principle: process; material: flash; concept or principle: moulding
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
Answer:
 material: be; material: material; concept or principle: surfaces; material: be; material: material; concept or principle: process; material: flash; concept or principle: moulding