It was my first to make a retaining wall with caps on.
I am just wondering if there is any way to fill up the gab between caps and paint it over.
Let me tag our resident retaining wall expert in @Adam_W to see if he might like to share his thoughts for you.
It would be good if you could update this discussion - https://www.workshop.com.au/t5/Outdoor/Pathway-on-top-of-soil/td-p/35175 - with some photos of what you have done so far.
Hi @dogbural , issue you'll have is expansion & contraction of materials (both the cap & the wall).
Any sealant will need to be flexible and you'll need to fill at a time when the materials aren't too beyond average (i.e. - not on a really hot or cold day or after timber has been in sun for hours).
It's not ideal as the paint will likely crack and there will be either bulging or stretching of the sealant.
Personally... I'd just aim for nice clean joins, leave them a couple of mm apart as expansion is the bigger problem and live with it.
Could you slice off a 'wedge' shaped piece of hardwood the same thickness and insert it into the gap with a flexible glue/sealant?