Keep it together: An evaluation of the tensile strengths of three select adhesives used in fossil preparation
Bibliographic record
Abstract
Abstract The tensile strength of a select group of common fossil adhesives (50% w/w Paraloid B-72 in acetone, Paleobond PB100, and Devcon 2-Ton epoxy) was tested over a period of 9 months. Because the testing process is destructive, the tests needed to be standardized to draw valid conclusions, and because large sample sizes were desired for the most statistically accurate results, limestone adherends were used as a proxy for real fossil specimens. Paraloid B-72 in acetone at 50% w/w demonstrated long solvent retention and took several months to attain full strength. Although it was the statistically weakest of the three adhesives, it still required a significantly large force to be exerted (275.56 lbs/in2; 19.37 kg/cm2) in order for it to fail after only 3 days. If fossil specimens joined with Paraloid B-72 are provided with appropriate archival support, then the adhesive will slowly attain full strength. Devcon 2-Ton epoxy was stronger than the limestone adherends and created minor or major substrate failure in the majority of samples, indicating that its use be restricted only to specific situations, such as heavy specimens that cannot be supported externally. Paleobond PB100 samples failed on average between 535 and 636 lbs/in2 (37.6 and 44.7 kg/cm2) and generally demonstrated adhesive failure, with some minor substrate damage. Paraloid B-72 demonstrated substantial tensile strength in this study and has excellent long-term stability and reversibility. Therefore, Paraloid B-72 should be considered the default adhesive in the majority of fossil preparation practices.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".