That Helen Frankenthaler painting damaged last week when a 12-year-old boy affixed a wad of gum to it in the Detroit Institute of Arts has been taken to the conservation lab. “Museum officials said they are optimistic that the picture will make a full recovery. But in contrast to comments earlier this week in which relieved officials said decisively that the 1963 painting, ‘The Bay,’ would be fine, the museum issued a more tempered statement.