In our home we used to(and still using) a small piece of cloth made into a lemon size ball to spread oil o the Dosa Tava. If we pour oil with a spoon, it will not spread into a uniform thin layer. Instead it may accumulate at the centre or at some side. For Dosa to come smoothly without sticking at any place, a thin layer of oil is needed on the Tava. This is facilitated by the small cloth ball touched with oil. By this just by on time touching the oil the cloth can be used for more Dosas and the spread will be uniform.
The new brush just tries to replace the cloth ball or cloth bunch. It can be used for many other uses also. For example when making certain sweets e need to grease the plates or vessels. with Ghee or oil.
In our home, we do not use the oil brush for host surfaces like Dosa Tava, but use it for cold surfaces like pre- greasing plates for making Burfi, etc.
If a product is useful it will find more buyers and will be successful, but if it is useful and affordable, it will fail and vanish.
Yes I have come across and we have bought many such items online. Most of them are cheap and have utility. One such is the kitchen rack for draining water from cleaned vessels. They are available in plastic and steel. Many such items are quite useful in small area homes like budget and utility flats etc.
As our house is a small area one, we have many such products which help us to have all needed facilities usable in a small area space.
One such notable product is a 'portable plastic commode' to be used in Indian type closet- converting Indian type closet to a Western Type closet. I was looking for such a product to use in our 1BHK flat in Mumbai as my wife could not bend or squat due to a fall she suffered. Searching online I found and bought it and it was a suitable, easily available, affordable solution for our problem.
Many times our necessity makes us find such products.
