Drying Rack & Dipper

[PODIGGER]

During my last couple of visits to the Peace River I found several large Proboscidean bones.  I was concerned about consolidating them due to their size.  With my previous preservation efforts I used cardboard to set my specimens on after giving them a vinac and acetone bath.  I had found that if I did not rotate the wet specimens I would wind up with drip marks and white blemishes where the bones actually would stick to the runoff liquid.  With this in mind I tried to come up with some type of drying rack and a tool to dip the large specimens into the solution with and retrieve them without touching the wet surfaces.  I came up with a small wooden ladder type configuration for drying that worked really well so I thought I would share it for anyone having a similar issue.  I also made a "dipper" out of a piece of closet rod and a metal utility hanger.  I finished the wooden rack with laquer to seal the wood and help keep it from absorbing the solution.  Cardboard placed underneath the rack caught and absorbed the runoff.  Below is a picture of the rack and dipper along with a photo of the specimens they were used for.  I used scrap wood I had on hand for the sides and purchased 24' of 1/2" dowel rod.  The dowels were cut down to 13" and then mounted 1/2" into the side rails.  You can see the last rod on the left is not a as far apart as the others.  This was due to using scrap "as is" for the sides.  I wanted to get a little more cross support so I added the last dowel on the left to fill to big of a gap.

 

 

 

[Ptychodus04]

Nicely done.

[PODIGGER]

Thanks Kris.

[digit]

Looks like a good system. Keep in mind that most of the consolidation is meant to seep into the porous bone and solidify the bone from the inside. Heavy amounts on the outside of the bone will end up giving it a 'glazed doughnut' sort of appearance. Most folks don't really care for the super glossy look on a bone and will often remove excess consolidant--Butvar, B-72, PVA (Vinac)--by soaking a rag in acetone and wiping down the surface to emulsify and remove excess resin on the surface. You might consider using a clean dry rag (can be purchased in bulk in the paint supply section of your local home improvement store) to wipe off excess consolidant before setting on your rack to dry. Mopping up the drippy excess while it is still liquid would minimize the amount of cleanup needed after the consolidant had dried.

 

 

Cheers.

 

-Ken

[Harry Pristis]

Does the lacquer on the wood dowels not react to the acetone??  Those drip pearls are a pain, which is why I rotate things with cancellous bone once or twice (for small fossils) on the cardboard.  Furthermore, pre-heating the bones serves to speed up the evaporation of the acetone while keeping the surface temperature above the dew-point.

[digit]

What's your preferred method of preheating the bones before a dip in the consolidant? I imagine an oven set at a low temperature would be more effective than a trip in the microwave which is more effective at heating water molecules.

 

 

Cheers.

 

-Ken

[Harry Pristis]

10 minutes ago, digit said:

What's your preferred method of preheating the bones before a dip in the consolidant? I imagine an oven set at a low temperature would be more effective than a trip in the microwave which is more effective at heating water molecules.

Cheers.

Ken

 

I usually heat specimens with an infra-red lamp to drive off moisture just before dipping the fossil. 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.  (More at my profile page --> About Me)

[PODIGGER]

Thank you for the info and comments gentlemen.  

Harry, 

Based on reading your previous posts I do heat the specimens before dipping.  I have used an infra red lamp and have also set up the whole process outside on a bright sunny day and let the specimens warm up in the sun before dipping.  The lacquer does not seem to have reacted at all with the acetone.  I tried it with some small fossils I really didn't care about first and found no issues.  With a large piece of cardboard under the drip rack any runoff has been caught and absorbed.

 

 I really appreciate the information I have found here on the Forum from both of you gentlemen.  It has encouraged me to try the consolidation process with what I think are very good results.  Thanks!