Nunaat Naat Brazilian Keratin Liquid Keratin Leave In Reconstructor, 10.1 fl oz

Can i use this product on just chemically /relaxed hair? Or is solely for those who have done keratin treatment before?

Sulfate free?

How often can i use this product?

I just bought this product but I don't use flat iron all the time. Can I use it on my hair like any cream instead?