omer ▁parts . ▁The ▁strength ▁of ▁bond ed ▁pow der ▁prints ▁can ▁be ▁en hanced ▁with ▁w ax ▁or ▁therm os et ▁polym er ▁im pre gn ation . ▁ ▁S tere ol ith ography ▁▁▁ ▁The ▁S tere ol ith ography ▁( S LA ) ▁process ▁is ▁based ▁on ▁light ▁cur ing ▁( ph ot opol ym er ization ) ▁of ▁liquid ▁materials ▁into ▁a ▁solid ▁shape ; ▁it ▁ ▁was ▁pat ented ▁in ▁ 1 9 8 6 ▁by ▁Ch uck ▁H ull . ▁ ▁In ▁this ▁process ▁a ▁v at ▁of ▁liquid ▁polym er ▁is ▁exposed ▁to ▁controlled ▁light ing ▁( like ▁a ▁las er ▁or ▁a ▁digital ▁light ▁project or ) ▁under ▁saf el ight ▁conditions . ▁Most ▁commonly ▁the ▁exposed ▁liquid ▁polym er ▁hard ens ▁through ▁cross - link ing ▁driven ▁by ▁the ▁addition ▁reaction ▁of ▁carbon ▁carbon ▁double ▁b onds ▁in ▁ac ry l ates .< ref ▁name = pd cs > Add itive ▁manufact uring ▁from ▁pre cer am ic ▁polym ers ▁Add itive ▁manufact uring ▁ 2 0 1 9 , ▁vol . ▁ 2 7 </ ref > ▁ ▁Pol ym er ization ▁occurs ▁when ▁phot opol ym ers ▁are ▁exposed ▁to ▁light ▁when ▁phot opol ym ers ▁contain ▁chrom op hor es , ▁otherwise , ▁the ▁addition ▁of ▁mole cules ▁that ▁are ▁photos ens itive ▁are ▁util ized ▁to ▁react ▁with ▁the ▁solution ▁to ▁begin ▁polym er ization . ▁Pol ym er ization ▁of ▁mon om ers ▁lead ▁to ▁cross - link ing