How to remove graphite safely from rock?

[sticksandstones]

Hi all,

 

I recently bought a dinosaur footprint, and it has a graphite outline. I was hoping it would just come off with an eraser, but it refuses to budge. I didn't want to just slap water on it and hope for the best. Is there a good way to remove the markings without damaging the footprint?? I'd love to display it natural.

 

Thanks so much for any help!

 

 

[caldigger]

I would try Isopropyl alcohol (rubbing alcohol) as strong as you can use. I get 91% from Walmart.  But before you try that, lets see what others have used in the past. They might have something better to use.    Really nice footprint by the way! 

[Raggedy Man]

Is the graphite naturally occurring in the fossil or was it placed there by the person who found it(by a pencil)? If it's natural I would see no reason to remove it as it adds a distinct margin between the impression and surrounding area. Adding solvents could cause discoloration and distort the matrix. If the graphite is natural removing it will destroy your specimen. You can heat it above 700 Celsius in which it will oxidize to form CO2. Graphite is soluble in molten nickel and chlorosulfuric acid. Either way, I think it's best to leave it be.

 

Best regards,

Paul

[caldigger]

Somebody outlined the print with pencil.

[Wrangellian]

I know graphite is tough to remove from a rough rock surface like that.. I'm not sure what to say. I wouldn't heat it! And any sort of acid is likely to ruin the rock too.

Have you tried a small scrubbing type brush with water or soapy water? Usually a bit of water won't have too much effect on the rock. The rock probably was subjected to water numerous times before being picked up anyway, but as a rule I agree that you need to be careful - I once had a shale fossil disintegrate in my hands after rinsing (after it had been dry inside my house for some time). That's why I suggest local application of water with a bit of careful scrubbing, but I have no idea whether that will work. It might leave a darkish smudge and I don't know if you'd think that was an improvement or not. Maybe put a pencil mark on the backside and try removing it there first, as a test.

[Raggedy Man]

I found a piece of discarded rock and decided to do an experiment to offer assistance. This should help with the removal of the wretched defacement of your specimen. I used Caldiggers suggestion of 91% isopropyl alcohol and a ridged plastic brush. The results are clearly evident. Please show after images of your results. I would work small areas at a time and do not allow the alcohol to sit there longer than needed. It will discolor the surface.  Thanks!

 

Best regards,

Paul

 

[sagacious]

The safest way to remove graphite from a hard stone surface is to use a grey 'ink eraser', and go slowly and patiently. Like all careful prepwork, it will take time. Graphite marks on hard stone won't erase easily as normally happens when eraser meets pencil mark. The 'pink pearl' pencil erasers are often too soft to remove graphite from a hard surface. The grey ink erasers have an ultra fine pumice added, and that's what is necessary to remove graphite marks from stone. Grey ink erasers can be purchased at any art store or office-supplies store.

[sticksandstones]

Thanks so much for the replies everyone (and the experiment Raggedy Man!!!)! I need to go to Michael's anyway, so I'll try the ink eraser first... It seems to be the least invasive method, so if that doesn't work, I'll try water then the isopropyl alcohol. I'll let everyone know which worked out and post pictures!

 

1 hour ago, Raggedy Man said:

wretched defacement of your specimen

 

Haha! Yes, they were pretty apologetic - their supplier from France always outlines the footprints if they don't call in advance and remind him not to. Why he would do that to begin with, not sure!

[DPS Ammonite]

I suggest using a less aggressive method first before trying the grey abrasive ink eraser. Try rubbing alcohol and a soft bristle toothbrush. Then try hydrogen peroxide instead of the alcohol.

[digit]

Before trying more aggressive chemicals I'd try something as simple as soapy water and a soft bristle toothbrush. If you are wondering if soap, alcohol, or hydrogen peroxide might damage or discolor the rock matrix, you could try a bit on a spot on the reverse of the footprint where it would not be visible if it affected the rock in any way. Maybe start with the toothbrush and just water and add some simple dish soap. I'd stay away from any hand soap that might have an oily "hand softener" additive mixed it which could stain the rock.

 

Let us know how you do and take some during/after photos. We'll all learn from your experiment.

 

 

Cheers.

 

-Ken

[Pagurus]

I don't know if it will work but if you're going to an art-supply store like Michaels you might want to get one of those soft gray "kneaded" erasers and try that before using the more abrasive ink eraser. The kneaded eraser can get into places the pink erasers can't reach and are really good at sticking to the graphite. They're fun to play with too. 

I've never tried them, though, on stone but I think it's worth a try. I'd try it on the back of your rock first just to be sure it doesn't stain. I don't think so, it doesn't stain paper, but it's best to be careful with whatever technique you try.  Good luck!

[JohnBrewer]

16 hours ago, Pagurus said:

I don't know if it will work but if you're going to an art-supply store like Michaels you might want to get one of those soft gray "kneaded" erasers and try that before using the more abrasive ink eraser. The kneaded eraser can get into places the pink erasers can't reach and are really good at sticking to the graphite. They're fun to play with too. 

I've never tried them, though, on stone but I think it's worth a try. I'd try it on the back of your rock first just to be sure it doesn't stain. I don't think so, it doesn't stain paper, but it's best to be careful with whatever technique you try.  Good luck!

 

Yeah, I agree. I use these erasers a lot. Putty erasers they're called. You can, as has been said, knead them to a point. They're also slightly tacky so you might be able to touch the marks and they may lift off. If they're too tacky keep kneading between thumb and finger and the tackiness will get less. I'd mark the back of the stone and try several methods before going headstrong on the print area. Living with the lines might be better than erasing both the lines and footprints tho! 

 

Best of luck and let us know what worked. 

[sticksandstones]

I'll probably be heading to the store today, so I'll let everyone know how it works out.

[ischua]

When I do painting restoration i remove a lot stuff off paintings with white bread. Its just wet enough, picks up dirt and soot with ease. You use it just like an eraser brushes right off

[sagacious]

On ‎10‎/‎2‎/‎2016 at 7:06 PM, DPS Ammonite said:

I suggest using a less aggressive method first before trying the grey abrasive ink eraser. Try rubbing alcohol and a soft bristle toothbrush. Then try hydrogen peroxide instead of the alcohol.

Be extremely circumspect before using solvents on absorbent stone. Using a liquid runs the risk of smudging the graphite and making the marks worse, without removing them. I found this out when trying to remove pencil marks from pottery -- solvents just carried the graphite particles deeper into the unglazed stoneware.

 

As I mentioned above, a grey ink eraser is the safest way to remove graphite marks on hard stone. The grey ink erasers are designed to remove ink and graphite from paper, and to do so without damaging the paper, let alone stone. A grey ink eraser worked for me to remove pencil marks on pottery, should work well on stone.

[sticksandstones]

Okay, so I got a variety pack of erasers, and after a couple tests either an extra soft white vinyl eraser or a gum eraser work best. As in, with just a couple seconds the marking was gone. The kneaded smeared a little before it erased and was a little sticky, so I'd rank it lower than the other two. However, once I started on the actual footprint, it didn't erase at all. I tried all three erasers and none took any hint of the markings off. I'm thinking maybe it was hit with fixative? If this is the case, how would I go about removing that, if it's possible?

 

Hopefully this thread will be helpful to others who want to remove graphite, if anything. The brand/pack I bought was General's Art Eraser Set for ~$5.

 

Here's the before and after for the vinyl eraser (pretty similar results with the gum):

 

[Fossildude19]

Hello,

I was going to ask how sure you were about the nature of the outline marks.

Did you question the seller about the origin of the outline?

It's entirely possible that it could have been hit with a fixitive, or, ... it could be some form of ink. 

 

I would try to get more information from the seller before trying anything else - and asking if they have any suggestions on how to remove it. 

Regards,

[sticksandstones]

The guy they get the footprints from outlines them with what he says is graphite. They didn't seem terribly happy about it and mentioned they ask him not to. I asked about the best way to remove it when I first inquired about the piece, and they told me that an eraser should work. I'll email them again and see if their supplier also uses fixative! They didn't mention it, though, so I don't think they're aware of it if he does.

[sticksandstones]

So I emailed the seller and they said they didn't notice fixative, but after they looked at one they have now, they said it's almost definitely been sealed. Mine is shiny in places also, so I'm thinking it's been sprayed. Is there a way to remove the fixative or am I stuck with the outline forever?

[ischua]

If a fixative was used you would need to know what kind. A few are removable but might wash the carbon in. I would try the ink eraser first . The next choice is steel wool and it is going to make a mess.  Both might cause damage, Its a hard choice is it worth the risk?  I think its on the seller too now... refund? reduce the price?... Its not what you payed for.

[tmaier]

Definately don't use steel wool. It leaves behind some of the iron, and changes color with age. It might look OK at first, and then some year later turns black or orange. Iron and steel tools often can make marks that don't show up for some years.

[Wrangellian]

It would help if there was some way to know what the fixative is, and I'm not sure what that might be either, but you could try using acetone to remove it, since acetone shouldn't affect the rock. Then if it works you can try one of the methods we've suggested for removing the graphite.

[tmaier]

I use Krylon "Workable Fixatif" (it is spelled that way on the can) on book repairs and I notice that high moisture like light dew will pull the stuff right up out of the fabric of the book cover. It isn't soluable in water, but water seems to bust it up and turn it into a white powder.

So it might not hurt to just soak the whole fossil in water for a couple days, then give it a light brush down with a soft toothbrush. The fixative might fall off. Depends on the chemistry. The stuff I'm using seems to be destroyed by water.

The idea of a fixative is to hold down powdery surfaces, like for chalk, charcoal, pencil and pastel drawings and the like. I like to use it to give a scuff protection and UV filter to the book cover.

A "non-workable fixative" is more of a permanent sealant than the "workable fixative". The non-workable fixative may require a solvant to remove.

[sticksandstones]

I emailed the seller to see if he knew what kind of fixative the supplier used, and he replied with this:

" It’s probably just some sort of polyurethane clear coat.  Mineral Spirits or paint thinner typically takes that stuff off, but I don’t think I’d mess with it to be honest. "

 

I guess I'll try a little water and acetone on inconspicuous areas and see if that removes the fixative without damaging the stone. I don't have mineral spirits or paint thinner around, as far as I know.