A hazard pictogram on a label does not by itself make a product dangerous goods for transport. Transport rules are separate, and the transport classification for each product is in section 14 of its safety data sheet.
What changes for regulated products
Corrosive products are not carried by Royal Mail. They travel by courier as limited quantities, whatever their weight.
Limited quantity parcels carry the limited quantity mark on the outer packaging.
If you ship your own orders, check that your courier accepts limited quantities before you list the product.
Our fulfilment service chooses the carrier by weight and hazard, and sends these products by courier as limited quantities.
Your next step: Check section 14 of the safety data sheet for each product you plan to sell online.