Janet Cook Lewis (June 17, 1855 – January 18, 1947) was an American portrait painter, librarian, and bookbinder who specialized in book conservation and restoration.

Lewis discovered a process for preventing disintegration of the bindings of books, the larger part of her active life having been spent in applying this treatment to the collections found in U.S. private libraries.

Lewis was a pioneer worker in the interests of a woman's apartment house; in 1896, the Martha Washington Hotel was the outcome of the work done.

She was educated at Toledo High School, studied portraiture in New York City, and attended Cooper Union for four years.

"Bachelor girls" became the popular phrase of the era, and the four women on West 23rd Street received a great deal of attention from the newspapers.

In this studio was established the Pen and Brush Club, which became the most notable organization of women writers, painters, sculptors and crafters in the U.S. Lewis was first to suggest the idea, and she was honored as the Founder.

[1] While busy painting portraits, Lewis did not lose the greater idea which had come to her earlier in her New York life — the establishing of some central home for women, one large building, cut up into living apartments.

Their mutual interest resulted in a definite plan of action, to build an apartment house with money raised by subscription from women.

When visiting the Hunt home one day, Lewis was invited to inspect the beautiful art work on some of the book bindings in the library.

After her husband's death, Mrs. Hunt desired to get the vast collection of architectural books classified and catalogued for the use of her sons, but was so dismayed by the size of the task, she looked about for someone competent to assist her.

Love for and sympathy with the inarticulate, as well as a desire to rescue objects of such priceless value, gave her the impetus toward inventing or discovering something that would prevent this decay and waste.

Living as she did in this atmosphere of books, she came to know the various diseases which attack old volumes, and tried to find some compound which would arrest the destroying effects of age and worms.

[1] Fortunately, she became aware of the work of Professor William Pennington, a noted chemist, who was called as an expert to analyze the geological deposit created by the washing up of a school of fish on the rank vegetation bordering the Gulf of Mexico.

One or two, who were willing to be convinced, permitted her to try her compound on some of their less valuable works, and the changed aspect of the worn old volumes, which had been given up as doomed to disintegration, impressed them.

Belle da Costa Greene, head librarian of the J. P. Morgan collection of old volumes and early manuscripts, heard of the work being done by her fellow-librarian.

Lewis was heartily recommended to Mr. Morgan as the ideal person to restore his library, in which thousands of priceless books were in danger from the countless perils which beset them.