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n <br />u <br />93 The letter from Lucas and Associates stated that when quarried the stone is light gray in <br />94 color, however, Joliet and Lamont Limestone contain clay that is laden with pyrite, which <br />95 is a sulfur compound. The oxidation of the pyrite over six months gives the stone its <br />96 characteristic yellow tinge. The cleaning of the stone will remove the oxidation and <br />97 return the stone to its original light gray color, however, with in about six months time <br />98 the yellow color will return with oxidation. What has been gained? My conclusion is <br />99 nothing. The color will return even if the stone is treated with a waterproofing repellent. <br />100 <br />101 There are various parts of the fagade that are somewhat fragile which power washing will <br />102 break off. The surface of the limestone was processed in a quarry and cut at a mill with a <br />103 shock pea effect, which causes dimpling. Power washing, I submit, will destroy a great <br />104 deal of the dimpling, thus, altering the surface, i.e., altering the building. As far as I am <br />105 concerned power washing should not be allowed nor should the applying of a sealer. A <br />106 — - sealer is nothing more then waterproofing which may cause more damage to the <br />107 limestone then it would prevent. <br />108 <br />109 KEN HERCEG: Whatever is done we are proposing tuck -pointing and repairs. <br />110 There is a product called "John M 70", it was the same repair product used at Notre <br />111 Dame and the Chicago Water Tower. <br />112 <br />113 We are ambivalent about the cleaning, but tuck -pointing and repairs will be made. <br />114 <br />115 The cleaning of the building was brought up because of various dark spots, mold and <br />116 leakage from downspouts. <br />117 <br />118 Mr. Ujdak is absolutely correct about the return of the color. By cleaning we were <br />119 attempting to get a more uniformed color. We are not against to leaving the building <br />120 alone. <br />121 <br />122 JOHN OXIAN: Mr. Ujdak should make a motion to amend the Certificate of <br />123 Appropriateness. <br />124 <br />125 CHERYL GREENE: The Commission can approve part of the Certificate of <br />126 Appropriateness application and deny the power washing and sealant. <br />127 <br />128 JOANN SPORLEDER: I have a question regarding the sealant. What was the <br />129 reason for cleaning and sealing the surface? Was it simply for appearances or is there a <br />130 dangerous accumulation of environmental pollutants on the limestone? If there is a <br />131 substance that does need to be removed from the stone, it should be cleaned with hand <br />132 brushes and not by power washing. <br />133 <br />134 <br />135 <br />136 <br />137 <br />138 <br />