Hardness additive comprising a four chelant mixture and block detergents containing said mixture to improve edge hardening

A method of improving solid block hardness comprising:

• combining
• A) a hardness additive composition;
• B) an alkalinity source;
• C) at least one surfactant;
• and
• D) at least one additional functional ingredient;
• mixing to form a homogenous mixture;
• and pressing in a mold to form a solid composition, wherein the solid is a block having edge hardness immediately upon pressing and removal from the mold, wherein the hardness additive composition comprises:
• 1) from about 5 wt-% to about 40 wt-% of at least one polycarboxylic acid polymer chelant comprising a polyacrylate or polyacrylic acid polymer or homopolymer;
• and
• 2) from about 60 wt-% to about 95 wt-% of an aminocarboxylate chelant mixture comprising ethylenediamine-N,N-tetraacetic acid (EDTA), methylglycinediacetic acid (MGDA), and L-glutamic acid, N,N-diacetic acid (GLDA);
• wherein the ratio of polycarboxylic acid polymer chelant(s) to L-glutamic acid, N,N-diacetic acid (GLDA) or salt thereof in combination with ethylenediamine-N,N-tetraacetic acid (EDTA) or salt thereof, is between about 0.17:1 to about 0.42:1.