Hi I used to have extensions done, and now I'm a lash technician! and id say that if you want to use mascara, you will almost certainly need to by an extension specific mascara. Reason I say this is when I had my extensions (before I qualified) I searched high and low for a water based mascara, and really struggled to find one. I ended up thinking 'I'm only going to use it occasionally, so it won't hurt' and went ahead and just used my normal mascara, but it really does make a big difference to how long they last. I sell xtreme lashes one, and I think flirties do them and Marvellash do them among others... but some of these only lash tech's can buy, (as in they are not available to general public) so maybe ask your lash tech whether they can get you one. x