We recently removed the wallboard in our attic and discovered cotton insulation. The insulation is fireproof cotton made by Lockport Cotton Batting Co, Lockport, NY. Is this product safe or should it be removed?

Cotton is a type of cellulose insulation. Cellulose or cotton can burn but it is treated to resist flame spread when used like you see it. I am willing to bet that the label you see contains the UL seal denoting the degree of flamability.

cellulose is more commonly used than the pure cotton but is a very good insulation and very safe, IMO, even though I hate to work around the stuff.

cotton insulation is made mostly from rag and waste cotton so it is very environmentally friendly ( OK, I suppose it would be hard to call any insulation enviro-un-friendly given the eneregy resources they save.
:D

I would not hestitate to have it in my home.

Now, get back to owrk and cover it back up!

Excellence is its own reward!

We too recently uncovered Cotton Batting Insulation during an upgrade to our very old house. This particular addition was built in the 1930's. It is very dirty when removing it, with cotton dust everywhere!!!
The product was called Lo-K by Lockport. One panel of it reads: Lo-K by Lockport, Better Insulation, Reproofed Cotton, Lockport Cotton Batting co. Lockport, NY, Established 1870.
If the mice can get in they find it to be a great home! We removed it all and upgraded it to newer insulation. What a great product before the foam and fiberglass insulation!