You can use a little water to thin Soto's Appliance + Porcelain Touch Up. Use a water dropper or something similar, so that you can control the amount of water. Start with a single drop, and vigorously shake the closed bottle, then see if you need more. It is best to go slowly and add individual drops, rather than adding several at once, and perhaps get it too thin. Alternatively, you can pour out a little paint onto something like a plate, and add water, a drop at a time, to just that small amount of paint. This way, the whole bottle will not be affected if you add too much water.
Any paint can thicken up if exposed to air (for example, if the bottle was accidentally not fully closed the last time you used it), but if the paint is dry and/or lumpy on arrival, it very likely got frozen during transit. If this is the case, please contact us with your name and order number, so we can issue a refund or replacement.