Adult xenomorphs blood is not acidic?

Excellent point regarding the hook that didn't melt Resurgence.

Continuity error, that's all I think

Just watched last night and that is a good point but I think it was an oversight. Actually if the blood corroded the spear the alien would have shot out into space just from the momentum and Ripley wouldn't have needed to flame it with the engines.

I remember one of the Marines getting burned after a Xenomorph was shot with a shotgun, causing acidic blood to get everywhere in Aliens.

We're talking about the first movie 

Agree with Xenowarrior and dk on this one. I think they just overlooked it.

Though I just watched it on youtube, here's the link: https://www.youtube.com/watch?v=U-mmbStFrAA

Now at 0:50 you can clearly see the wire from the spear gun attaching the Alien to the ship. From there, it repels back to the door.

At 0:56 we then see briefly the Alien using it's tail to latch itself inside the thruster. After that Ripley burns him out and into space where we don't see a wire attached to him.

I guess we can assume the Alien was shot, as it repelled back to the door, the acid blood burned the wire, then the Alien used it's tail to latch itself inside the thruster of the ship to remain safe.

Just a hunch lol.

Guess the harpoon is more resistant, and it takes longer than 13 second to effectively corrode it.

What if the hook were comprised of a metal that was highly resistant to concentrated acids? Maybe something like Hastelloy-B, having a corrosion rate of <0.02 inches/year. 

Maybe the hook was shot through body armor where blood doesn't flow

wrong thread- oops

The force alone from the harpoon gun and the initial penetration would propelled the xenomorph out of the spacecraft.

The argument could be made that it is less caustic as they age. Hicks and Hudson only got minor surface burns when they got sprayed by an amount that are through three Nostromo decks.

Myrddin - "Hicks and Hudson only got minor surface burns"...  In case you missed it, we just got our asses kicked pal!

I've been keeping up with current events ;)

Couldn't resist lol.

Back to the topic, I just think it was all an overlook unless you want to get REALLY scientific and argue that the vacuum of space prevented the acidic blood from burning as it normally would, hence the Alien just repelling back to the ship, then crawling into the darkest hole possible to await what to do next.

A lack of oxygen is actually a viable reason for a lack of reactivity. Most corrosion involves some form of oxidation.

Exactly. So if we go that route, the acidic blood didn't have enough oxygen to act corrosively in the vacuum of space, hence why the alien was able to make it to the thruster and not be launched out into space after being severed form the cable. 

The way it interacted with human tissue was probably an oversight/practical effects issue.