1652
It was found later that other , stronger polymers could be used in this way provided the casting shells were strengthened and the burnout conditions were modified .
 material: polymers; material: be; machine or equipment: casting shells; process characterization: burnout conditions
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: polymers; material: be; machine or equipment: casting shells; process characterization: burnout conditions