I will take it that since this sap is an issue this must be some kind of Pine tree log sections (aka bolts)...?
The fastest way I deal with this for parks, camps, and landscape projects of this nature are to just recut them with a chainsaw taking off about 1/2" to 1" which makes fast work of getting rid of the sap stain and ooze, plus I get (usually) a flatter and more uniform surface...
If you don't have a chainsaw with a large enough bar, a 4.5" angle grinder with a sanding head and coarse grit sanding pad will also make short work of this task...as will a sharp smoothing plane...
I use a citrus-based solvent to soak the top and then a UV stabilized natural oil, pine Rosine, beeswax finish. The citrus solvent does a very good job of penetrating the wood and thinning out the remaining sap, and the oil finisher I use tends to react well with the sap stopping or greatly mitigating further bleed out of sap unless the tree was really pitchy or just freshly cut...
Tosa Tomo Designs
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