Yas feem ntau muaj lwm yam khoom uas tau hu ua fillers.Fillers yuav ua hauj lwm los ua kom ntau thiab kom pab tau cov khoom xav tau. Cov yas ntim quav yuav ua kom zoo dua thiab tuav ze dua kom tsim tau qhov ntev, vim cov yas shrinkage yuav txo. Ntoo hmoov nplej yog cov hom phiaj-feem thiab feem ntau yog siv cov ntsaws. Paj roob frock, uas ua los ntawm paj rwb linters, ua rau kom muaj zog. Rau siab zog thiab tsis kam mus rau kev ncaj ncees, paj rwb ntaub ntim rau hauv seem 1/2 nti square yuav ua tiav nrog cov yas. Asbestos fiber kuj siv tau los ua cov zauv rau cua sov thiab hluav taws kub, thiab mica yog siv rau molding yas nrig nrog superior dielectric yam ntxwv.xav fibers, silicon, cellulose, av nplaum los yog nutshell hmoov kuj siv .Nutshell hmoov siv siv ntoo hmoov nplej uas yog siv cov roj qaub ncaug zoo dua. Cov khoom siv qis siv luv luv yuav ua rau cov nqi qis dua, hos cov neeg uas muaj fiber ntau cov hluav taws xob muaj zog ntau dua qub .Qhov lwm yam, tsis xav ua cov fillers, xws li dyes, pigments, lubricants, Tsav tsheb thiab cov khoom yas yeem tuaj yeem raug ntxiv.
Plasticizers yog ntxiv rau muag muag thiab txhim kho cov moldability ntawm plastics.Filler thiab moulding cov neeg ua hauj raug ntxiv thiab tov nrog cov yas yas ua ntej nws tuaj molded los yog tsim.