We have removed thick ivy from the walls of our 20yr old brick built house. No damage to bricks or mortar, but despite use of scraper, wire brush, brick acid, flamegun, algon etc, we are unable to get rid of the residue of aerial roots. Any ideas please! In desperation we are even thinking of replanting ivy! but would rather not as a)we have lovely climbing roses which we'd rather not 'mask', and b) the ivy was really thick and populated by birds (v noisy dawn chorus) and spiders!