Butvar artifacts.

[TrilobiteAndrew]

Every time I use Butvar in acetone (10% w/v) on a fossil, I get a white milky residue that is very difficult to clean off.

 

I was told that the relative humidity had to be below 50% to avoid the white residue, but in Florida that does not happen that often.

 

Questions:

1) How can I pull off the white residue without damaging the mammal fossil (manatee skull)?

2) Will a 5-10% PVA solution in ethanol work better in a high humidity environment than Butvar?

3) Would dissolving Butvar in ethanol work better than in acetone for the white residue?

 

Any help is appreciated.

 

Thanks.

 

TrilobiteAndrew

[Brett Breakin' Rocks]

3 hours ago, TrilobiteAndrew said:

Every time I use Butvar in acetone (10% w/v) on a fossil, I get a white milky residue that is very difficult to clean off.

 

I was told that the relative humidity had to be below 50% to avoid the white residue, but in Florida that does not happen that often.

 

Questions:

1) How can I pull off the white residue without damaging the mammal fossil (manatee skull)?

2) Will a 5-10% PVA solution in ethanol work better in a high humidity environment than Butvar?

3) Would dissolving Butvar in ethanol work better than in acetone for the white residue?

 

Any help is appreciated.

 

Thanks.

 

TrilobiteAndrew

@Ptychodus04

[Wolf89]

@RJB

[Ptychodus04]

@TrilobiteAndrew, you can remove the surface discoloration with acetone. This will remove the Butvar from the surface of the fossil without damaging the consolidation. Simply brush it on and wipe it away with a white lint free cloth. Old white t-shirt material works well for me.

 

The ethanol might solve this due to its lower volatility as compared to acetone. The white is caused by moisture being trapped in the solution as the solvent evaporates.

 

@Brett Breakin' Rocks thanks for the tag.

[Harry Pristis]

I always heat specimens with an infra-red lamp to drive off moisture just before dipping the fossil in the Butvar B-76 solution.  I do this with all sorts of fossils, and have never had one damaged by the heating. The untreated specimen is always at least as wet at the relative humidity of the air around it, I surmise. (A microwave oven may be as effective, but I've only dried glass beads for my air-abrasive unit.) Residual moisture may cause a white film to develop on the surface of a fossil after dipping in the consolidant.

 

Here's how the white film forms: As the acetone in the consolidant evaporates, the temperature at the surface of the specimen chills abruptly, lowering the dew-point at which ambient water vapor condenses.

 

And, that's my theory -- that the white film has two potential sources: residual interstitial moisture and ambient humidity condensing at the surface chilled by evaporation.

 

   Think about a plastic bag of food placed into a freezer, where frost is moisture and bag is the film of consolidant. Frost can form on either or both sizes of the plastic bag, inside frost from moisture in the food and outside frost from atmospheric moisture.

 

   My strategy is to heat the specimen to drive off residual moisture, and consolidating while it is warm to avoid the dew-point at the specimen's surface, inhibiting condensation as the acetone boils off.

Do NOT heat the acetone solution directly. The acetone solution will get warm after dipping a number of heated fossils. You must have good ventilation to deal with the fumes

 

[SailingAlongToo]

50 minutes ago, Harry Pristis said:

 

Do NOT heat the acetone solution directly. The acetone solution will get warm after dipping a number of heated fossils. You must have good ventilation to deal with the fumes

 

And, a fire extinguisher and/or a box of baking soda handy to extinguish any oooppppsss! 

[Harry Pristis]

21 minutes ago, SailingAlongToo said:

And, a fire extinguisher and/or a box of baking soda handy to extinguish any oooppppsss! 

 

You must avoid any oops with acetone.  The fumes are EXPLOSIVE, not merely flammable and toxic.  Treat the acetone like you would treat gasoline.  Ventilation is everything in dealing with acetone.  It's self-defeating that moving air over a consolidant-wet fossil will increase the rate of evaporation, lowering the surface temperature, and increasing the likelihood of the white film developing.  My answer to this problem is to heat the fossil before consolidation.

 

 

[Ptychodus04]

6 minutes ago, Harry Pristis said:

 

You must avoid any oops with acetone.  The fumes are EXPLOSIVE, not merely flammable and toxic.  Treat the acetone like you would treat gasoline.  Ventilation is everything in dealing with acetone.  It's self-defeating that moving air over a consolidant-wet fossil will increase the rate of evaporation, lowering the surface temperature, and increasing the likelihood of the white film developing.  My answer to this problem is to heat the fossil before consolidation.

 

 

Agreed. you don't want a heat source near acetone unless you have some really good life insurance and a family that you want to set up.

[Harry Pristis]

13 minutes ago, Ptychodus04 said:

Agreed. you don't want a heat source near acetone unless you have some really good life insurance and a family that you want to set up.

 

I think that "heat source" is too broad a caution.  More specifically, some ignition hazards are sparks (such as from electric motors) and heating elements (such as in a space heater).  I need not mention smoking tobacco or anything else while working with acetone, do I?   Of course, these ignition hazards are not dangerous unless the concentration of acetone fumes reaches some critical level such as you might find near the mouth of the consolidant container or at the surface of a consolidant-wet fossil. 

 

I use an infrared lamp for heating fossils.  My assessment is that the infrared lamp is not a serious ignition hazard, but I never leave it unattended when lit.  Even then, I use a large, thick ceramic bowl as a stage for the fossils to be heated.  I use two industrial fans to evacuate the fumes.  I am sensitive to the fumes, so they never approach a dangerous concentration when I am working.  (My expectation is that everyone will be sensitive to acetone fumes.)

 

I repeat, ventilation is everything when working with an acetone solution. 

 

[Ptychodus04]

8 hours ago, Harry Pristis said:

 

I think that "heat source" is too broad a caution.  More specifically, some ignition hazards are sparks (such as from electric motors) and heating elements (such as in a space heater).  I need not mention smoking tobacco or anything else while working with acetone, do I?   Of course, these ignition hazards are not dangerous unless the concentration of acetone fumes reaches some critical level such as you might find near the mouth of the consolidant container or at the surface of a consolidant-wet fossil. 

 

I use an infrared lamp for heating fossils.  My assessment is that the infrared lamp is not a serious ignition hazard, but I never leave it unattended when lit.  Even then, I use a large, thick ceramic bowl as a stage for the fossils to be heated.  I use two industrial fans to evacuate the fumes.  I am sensitive to the fumes, so they never approach a dangerous concentration when I am working.  (My expectation is that everyone will be sensitive to acetone fumes.)

 

I repeat, ventilation is everything when working with an acetone solution. 

 

Well said Harry. I prefer to be more general when discussing explosive chemicals and acids with an unknown audience. 

 

I agree about fume sensitivity. I’m not extremely sensitive to them but I want as little exposure as possible. 

 

[RJB]

27 years now, and to this day, I have never had a problem with Glyptal. 

 

RB

[Harry Pristis]

2 hours ago, Ptychodus04 said:

Well said Harry. I prefer to be more general when discussing explosive chemicals and acids with an unknown audience. 

. . . 

 

Yes, I understand.  I don't mean to scare new preppers, but the reference to an "oops" with acetone seemed dismissive.  I think that we need an objective view of dealing with acetone.

 

31 minutes ago, RJB said:

27 years now, and to this day, I have never had a problem with Glyptal. 

RB

I am puzzled by this Glyptal reference.  Surely, you are diluting the Glyptal with acetone for consolidation purposes.  (I assume you are not using it unthinned to coat motor windings.)  I have a few fossils in my drawer which are consolidated with Glyptal.  I can pick them out because they are yellowed somewhat.  My Glyptal experiment was more than 35 years ago, before I switched to Butvar B-76.

[Ptychodus04]

39 minutes ago, Harry Pristis said:

Yes, I understand.  I don't mean to scare new preppers, but the reference to an "oops" with acetone seemed dismissive.  I think that we need an objective view of dealing with acetone.

Agreed. I used to have a cavalier approach to acetone before I read more about it and discovered how totally nasty it is! We used to degrease our hands with the stuff when I was a kid.

[TrilobiteAndrew]

To All who replied:

 

Thanks for the information.

 

So, at least I know that others have the same problem, if precautions are not taken.

 

I use an extremely well-ventilated garage (with fans) for the Butvar-76 treatments.  But pulling off the white crystallized Butvar-76 after it hardens on the fossil is a lot of work.  When I remoisten the fossil with fresh acetone, the whiteness goes away....until you let it dry again.   It is always a good idea not to have this happen in the first place.   I have treated numerous fossils with Butvar-76 in acetone with excellent results.   But this last go-around, the manatee skull (partial) looks like it got snow on it.   So, I have a challenge to get the white Butvar off.

 

I am ordering an air abrasive system soon and may wait to see if I can pull off the white butvar residue with that, before going back to soak the fossil in a pan of acetone.

 

TrilobiteAndrew

 

P.S.  I have a chemistry background, so there is no need to caution me about acetone.....it is a nasty volatile material that must be respected.   I will also try dissolving Butvar-76 in ethanol, and see if that works better.

[Harry Pristis]

Good for you, Andrew.  Keep in mind that lots of potential preppers will read this thread for a long time.  Some of them may benefit from our collective experience.

 

I am uncertain of the nature of your problem with the manatee bone.  It sounds like your problem is twofold:  You've trapped moisture in the plastic and you can't readily remove the surface film of plastic. 

 

If the light application of raw acetone to the white film doesn't solve the problem, it may be that the consolidant solution is too thick -- that is, there is too much plastic.  The consolidant should be watery, no thicker than enough to slightly retard air bubbles rising to the surface.  Don't forget that the solution grows thicker as the acetone boils off, leaving the plastic behind.

 

Then, too, dissolving the B-76 in the acetone is a challenge requiring extended shaking or stirring.  You didn't accidentally apply a 'snot' of undissolved plastic to the bone, did you?

 

Anyway, good luck with your project.  Let us know how it works out.

 

 

[RJB]

On 12/27/2018 at 9:08 AM, Harry Pristis said:

I am puzzled by this Glyptal reference.  Surely, you are diluting the Glyptal with acetone for consolidation purposes.  (I assume you are not using it unthinned to coat motor windings.)  I have a few fossils in my drawer which are consolidated with Glyptal.  I can pick them out because they are yellowed somewhat.  My Glyptal experiment was more than 35 years ago, before I switched to Butvar B-76.

Hi Harry,  Yes I do cut it with acitone and I to this day have not seen any of what ive coated with glyptal is yellowed one bit.   

 

RB

[TrilobiteAndrew]

Dear Harry:

 

I have been using a 10% Butvar in acetone (w/v) for years but I have begun to think that I need to change two things: (1) First, reduce the amount of Butvar down to 5%, and (2) switch to ethanol so that the evaporation goes more slowly.

 

I am also suspecting that I am trying to apply too many coats of the Butvar at one time.

 

What is your protocol?  Do you have a set limit to how many coats you apply?  I tend to keep applying the Butvar as long as the fossil keeps absorbing the solution. 

 

Thanks for the tips.

 

P.S.  I will start posting a set of photos of my trilobites, so stay tuned.   I am just getting started now.

[Harry Pristis]

Coats of Butvar B-76?!?  You shouldn't be "coating" vertebrate fossils, you should be impregnating them with consolidant, soaking them until they won't absorb any more fluid.  My protocol is available through a forum search for "preserving fossils" or you can go to my profile page here and click on the "about me" button.  http://www.thefossilforum.com/index.php?/profile/42-harry-pristis/&tab=field_core_pfield_11

[TrilobiteAndrew]

Harry:

 

I get this definition from the website, "The PaleoPortal:"

 

"Consolidant - an adhesive, often in a volatile carrier solvent, applied to soak into a specimen and force subsurface adhesion."

 

I was instructed several years ago to use 10% Butvar-76 in acetone to "both" consolidate and strengthen a fossil....AND...as a final layer on the outside when the fossil stops taking up the original applications.

 

But after a few coats, the white artifact shows up more frequently..

 

So, was this bad advice?  AND...should the Butvar-76 consolidant be 2-3% in acetone and the final layer be slightly higher?

 

I plan to read your link above for preparing fossils tonight.

 

And thanks for the communications.

 

TrilobiteAndrew