Dissolving Arrowheads with Hydrofluoric Acid

foreign [Music] welcome back to Cody's lab so today I have some arrowheads I've always wanted to see what happens if I put these in hydrofluoric acid those are the scary stuff that dissolves glass these are a glass-like material so it should dissolve them the question is what's going to happen as it's dissolving will it reveal any kind of interesting patterns or will it just dissolve it kind of smoothly what about the sharp edge will that be blunted by the acid or will it get even sharper I don't know today we're gonna find out now don't worry these are not antiques they were made very recently using traditional techniques by my friend Joseph from good and basic I have a few different kinds so this is black obsidian you can see the light does not go through it very well it's actually a snowflake black I have another piece of it here with the snowflakes there I will try to dissolve a piece of this to see what it does to the actual snowflake portions this is a green obsidian which lets a lot more light through as you can see [Music] this one is made out of Flint and this one is made out of agate the Agate lets a lot of light through Flint not very much a little on the edge there when it's thin so let me uh set up and uh we'll see what happens when we put them in acid okay so this acid is able to dissolve glass metal ceramics flesh but it is powerless against plastic which is why everything I'm using here is made out of plastic I've also got this tub full of lime catch any drips neutralize the acid any Vapors I produce should be pulled away by the fan you can hear running was just to transfer some of this into these soda cups the bottle cups I guess plastic of course holds up to the acid much better than a glass Beaker wood okay I'm actually going to dilute the acid about 50 with distilled water so let's make an acid about 20 concentration I'm mostly doing that to save acid and to make the the solution more efficient if so I don't have to use quite as much I'm already using quite a lot okay we're also kind of rinse out my Beaker there for the obsidian so this is the snowflake kind of looks like eyes don't normally in the acid no not the acid let's raise the level list a little bit there perfect okay oops all right a little therefore the other two in there's the foot hey let's let those sit the Flint's already lightning in color so it's been about four hours I've come out to have a check on it and the Flint has dissolved a significant amount you see it's come off the nylon string there Solutions change color there's a little bit of sediment there interesting oh came off the string yep this one's looking a lot rounder these don't look all that different so it's the next morning about nine hours since I put them in the acid definitely has affected them these two especially much dissolved that that arrowheads looking a lot rounder smaller it's still hanging on though it's uh pull them out get a better look at them my scheme to pull them out with a string clearly did not work so I'm going to use some chopsticks grab hold of the little piece of Agate that's left here there's something there I'm gonna dip it in some lime water to initialize the acid I could safely be handled put the rest of them out that was still on my string oh that's interesting it's got crystals growing on it let's have a look at the solutions that are remaining you see the one that had the Flint has got some reddish brown sediment to the bottom I'm guessing that's mostly calcium fluoride with a little bit of iron staining stuff that isn't dissolved by the acid the Agate has similar but instead of it in this one barely see is basically pure white doesn't have that iron in it that's really the difference between Agate and Flint Agate is a more clear the chemically they're basically the same they're both made of calcidoni and these two you can see the solutions are a little bit dark Maybe even greenish greenish Gray there's not much in the way of sediment but the solutions are kind of Cloudy I don't know how that shows up on the camera there it is I'll just uh dispose of this acid what I'm going to do is just react it with lime water make calcium fluoride which maybe I'll use as a flux later effective in fact I've got a bucket right here just for that so here we are I've washed the acid and the fluoresilicate crystals off of them you can see that they are definitely changed see here's some pieces that didn't go through the acid you see there's quite a difference the obsidian is now dull it's not shiny anymore the Flint is a lighter color also dissolved away significantly same with the Agate I think the outer material is on this I think that's calcium fluoride I think there's I think there's more calcium in these than there is in the obsidian except for the snowflakes you see the the eyes here there's some of that white material here looks like calcium fluoride so there must be calcium in the snowflakes now you'll notice that the obsidian arrow point didn't get as small as the Flint or the Agate Arrow points did even though they started about the same size and I think the reason for that is not that the obsidians any harder to dissolve but there was just more obsidian there for the acid to work on because I had this other piece in there with it so it kind of acted as a shield to protect it a little bit but also the obsidian it seemed to have gotten thinner see it dissolved in from the flat sides more than it did from the edges or maybe it did the same but you know it's more noticeable on the flat side and with the result of that is it's now much thinner you can see light passes through it more easily and it's a lot sharper than it was I well it certainly didn't adult see look at that cuts the paper perfectly and actually this other obsidian kind of did something similar if you look at the edge here oh well you can see that maybe you should get a magnifying lens here you see the edge it's all one Edge now and it's very sharp whereas the arrow point it didn't go through the acid The Edge is kind of is still sharp but it's sharp in many places it's more of a serration you can see the result is it's able to cut through the paper a lot better than it did before so this is the one that didn't go through the acid see it can't cut the paper at all for maybe a very edge so the acid does sharpen it significantly and while we're looking at this with the magnifying lens see if I can get that back on there you can see the working snowflakes have like a halo around them kind of a portion is like different than the rest of the obsidian also the obsidian seems to have lines in it now like styrations see most predominantly in this one now I think that might be one of the reasons maybe along with the snowflakes that this type of obsidian was much harder to nap I remember him telling me that it wasn't working very well you know this stuff was going much better so it was much more difficult to nap probably because of these defects which we can now see you can also see that there's little pock marks you can see it a lot better than this one places where the obsidian dissolved more easily so there is a pattern that was developed it's kind of neat this one the pox are smaller a bit more crater-like I guess almost looks like the surface of the Moon a little bit of course the freshly broken obsidian then you didn't go through the acid is completely smooth and glassy so anyway uh the Flint piece you can see it's doesn't really have those it dissolves more smoothly I guess more like it just shrunk it down the other calcidoni it seems to have had some like veins going through it you can see there places where it was more difficult to dissolve anyway there we have it that's what happens when you put an arrowhead in hydrochloric acid I hope you enjoyed

Channel: Cody'sLab

Views: 166,057

Keywords:

Id: 6uv-ih1GkJk

Length: 17min 10sec (1030 seconds)

Published: Tue Nov 01 2022