What to fill hardwood door with?

[Golaboots888]

One of the buildings that I look after dates from the 1870s. We have a presumably orginal door that is of 'slatted' construction with boards that are butted up to one another.

There is some separation of these boards now and I'm unsure what would be the best product to fill them with. It appears that there was something added previously which is coming away, it's slightly soft, more like frame sealant than a PVA type product.

Any recommendations greatly appreciated. Ideally something that's easy to apply, binds the boards together and fills the gap nicely.

 

[Burnerman]

Although It may fill the grooves if you overdo it, consider elastic type car body filler. Dries in 20 mins, remains flexible and dead easy to sand!
John

 

[KenGMac]

Golaboots888, good evening.

Possibly not what you are looking for but?

Given we have and in some parts of the UK and are in what passes for a heat wave, dry. hot Etc.

If it were me? i would do nothing at present at all, once the rain starts [and fails to stop] the door panels will absorb water and close up.

My back gate, is full sunshine I see that the slats have shrunk considerably, they will re-expand when the rain comes.

Ken