Great question about scoring, I'll bite
. Contemporary studies focus on the smoothness of the wood, and Planed Surfaces vs Sanded Surfaces as it relates to adhesion strength (mainly shear). I consider it presumptive that scoring is no longer believed to provide a better PVA glue joint with wood, as it is no longer (and for quite some time has not been) included in studies of PVA glue joint strength. The referenced paper (file size too large: https://www.researchgate.net/publication/355131920) includes references to other papers and articles discussing the subject, without the topic of scoring. Damaged and misaligned fibers appear to be a main detractor to a strong shear joint.
Excerpt:
A rougher, but clean surface (without damaged fibers),
can provide enhanced capillary forces and expose more porous structure in the wood [14]. .
REFERENCE: DRITAN, AJDINA: The influence of sanding process on adhesive bonding of wood. Agricultural University of Tirana; Albanian j. agric. sci. 2021;20 (2): 35-39
I do my own adhesion testing as there are so many variables and so much "information" on the internet (materials, glue type, wood characteristics, size and orientation). I bought a force gauge on Ebay to legitimize my adhesions tests. You can do your own adhesion testing, subjectively, with popsicle sticks and glue (or spruce, or rosewood or cellulose binding on Walnut, ect.), if you're so inclined. I've learned much about adhesion since I started doing this, and I can test the effectiveness of the glues on my shelf too. I highly recommend adding this to your building arsenal.
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References in that paper:
1. Jaic M, Palia T, Djordjevic M: The impact of surface preparation of wood on the adhesion of certain types of coatings. Zastita Materijala 2014, 55 (2): 163–169.
2. Sabrina AM, Cláudio HS, Joana M, Mário RS: Bonding behavior of Eucalyptus benthamii wood to manufacture edge glued panels. Maderas Ciencia y Tecnología 2013, 15(1): 79–92.
3. Svetka K, Julie C, Roger EH: Evaluation of two surfacing methods on black spruce wood in relation to gluing performance. J. Wood Sci. 2013, 59: 185–194.
4. Lütkemeier B, Konnerth J, Militz H: Distinctive impact of processing techniques on bonding surfaces of acetylated and heat-treated beech woo and its relation to bonding strength. Forest Products Journal 2018, 68 (4): 372–382.
5. Gardner DJ, Blumentritt M, Wang L, Yildirim N: Adhesion Theories in Wood Adhesive Bonding. Rev. Adhes. Adhes. 2014, 2 (2): 127–172
6. Cheng E, Sun X: Effects of wood-surface roughness, adhesive viscosity and processing pressure on adhesion strength of protein adhesive. Journal of Adhesion Science and Technology 2006, 20 (9): 997–1017.
7. Forest Products Wood Handbook – Wood as an Engineering Material. US Department of Agriculture Forest Service; 2010
8. Creswell WJ: Research Design-Qualitative, Quantitative and Mixed Methods Approaches, Second Edition. SAGE Publications Thousand Oaks, London, New Delhi; 2003.
9. Kollmann FFP, Kuenzi EW, Stamm AJ: Principles of Wood Science and Technology – II –Wood Based Materials. Springer-Verlag Berlin, Heidelberg New-York; 1975.
10. Shields J: Adhesive handbook, 3rd edition. Butterworth & Co (Publishers) Ltd; 1984.
11. Ajdinaj D, Kortoçi M: Curriculum development under the focus of industry challenges. 4th Annual International Conference on Education and New Learning Technologies, Barcelona, 2-4 July, 2012.
12. Fellin M, Hernández RE, Negri M: Surface process effect on PVAc glued joints. 2nd International Scientific Conference on Hardwood Processing, Paris, 29 September, 2009.
13. EN 205: Test methods for wood adhesives for non-structural applications. Determination of tensile shear strength of lap-joints. CEN, Brussels; 1991.
14. ISO 13061-2: Physical and Mechanical Properties of Wood – Test Methods for Small Clear Wood Specimens: Part 2: Determination of density for physical and mechanical tests. International Organization for Standardization, CH-1211, Genève; 2014.
