Are glue ups different between soft and hard wood?

Question

I have some 300 yr old pine that I want to make a table out of. I was thinking of ripping into 6" wide sections and gluing together. I might leave some live edge on two long outside edges. The table will be 63"x 35". I'm wondering if there is much difference between the soft pine and a hardwood for glue ups?

Answer 1

I'm wondering if there is much difference between the soft pine and a hardwood for glue ups?

There is some, but from a practical workshop perspective there can be no effective difference. The key things still apply:

• Well-jointed edges that are dead straight or slightly hollow (a sprung joint/spring joint).
• Glue your edges while they are fresh¹.
• Apply the glue and get the joints together pronto².
• Alternate clamps top and bottom and/or use cauls or other aids to help keep the glue-up flat.
• If using any type of PVA, yellow or white, apply plenty of clamping force. PVA glues only produce maximum joint strength when high clamping pressures at the joint face are exerted.
• Use clamping blocks if necessary to avoid the clamps denting the wood (note: you will have to arrange something custom shaped for this purpose if you want to retain the live edge/waney edge on the outer two edges).
• Do a dry run before reaching for the glue!

Glueing differences between softwoods and hardwoods?
In general there's no special consideration for softwoods. There is however some difference in ideal clamping pressures for soft wood and hard wood ;-)

Multiple press releases and technical notes from Franklin, the makers of Titebond, give ranges of ideal clamping pressures but here's the table I've seen which makes it most plain that it's about wood hardness and not strictly wood type (as some people tried to make this about):

^{Longleaf pine, eastern red cedar and especially yew, all softwoods, are noticeably harder than a few commonly used hardwoods, including poplar, alder and esp. paulownia.}

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¹ Within the hour, but under 15 minutes would be ideal.

² Applying glue to only one side of a joint and/or waiting too long before bringing the two pieces of wood together are common reasons for sub-par joint strength, especially in combination with under-clamping.