I presumed you did use firewands.
From the tenor of your post, it sounded as though you had poured the alcohol onto your sub's body to get the x-shape. Pouring alcohol onto someone is iffy (as you pointed out, this is a BDSM forum, but it doesn't mean you are careful, either). Poured alcohol can pool and cause burns in some odd places, it can also soak into the furniture when poured and set fire to the bench the sub is on. In addition, in reading posts here and on other forums, there appear to be folk on here who think SSC and RACk are for wimps, while I'm not implying you think that, someone reading these posts might, and might think I'm being over cautious, and where fire is concerned, I think people should be overcautious. I've seen people do some pretty chancy things with fire. I tend to be very careful with fire - I love doing fire play, but was badly burned as a child, and tend to take a very cautious when using flames anywhere near anyone else.
And lol - you could have been using kevlar flogs, rather than firewands.