Merriam-Webster implies that the comparative and superlative for black are blacker and blackest. However, my native British colleague says he would never used blacker, only more black.
How common is using single-word comparatives and superlatives for color-designating adjectives? Is it used for some colors only (like white) whilst not for others (like black)?
Would you use the following sentences, or would you replace the single-word comparatives and superlatives with their compound version (more ..., most ...)?
Our toner is blacker than the ones from other companies.
Eco-terrorists fight for greener world.
After using this toothpaste your teeth will be whiter.
He is undoubtedly a nobleman with the bluest possible blood.