How to remove excess mortar from the cinder block wall i just installed?

I got done putting up my retaining wall about two weeks ago. In some places around the joints there is left over dried mortar. Is there any way to remove this, I have already tried a wire brush and a rub brick without much improvement other then taking away the textured look, its a cinder block wall so all the little nook and cranny's are filled with the mortar. would an acid solution work because i have read it can ruin the block itself. Any help would be helpfull thanks!! Here is a picture of what im dealing with not my wall but the same idea. Scroll down the page and u will see the pics. a href="http://www.renovateforum.com/f210/filling-mortar-lines-then-paint-74434/" rel="nofollow"http://www.renovateforum.com/f210/fillin…/a