Orange Goo....

It's a wood fungus.

My weeping Silver Birch trees attract it on old dead branches. Also have seen it many times on pieces of old timber/wood that have been left lying around in damp conditions, like alongside of houses etc etc.

Cause - Water leak/s somewhere, maybe when cleaning that benchtop down.

How do you get rid of it in the caravan you have shown - I would respectfully suggest there is no other way than pulling that wall lining off from the corner area shown and then cutting the affected areas out. It might even go down under that bench top.

If ignored it will eventually work its way through the existing wood that it has attached itself to just like rust in steel and is also a slow mover like rust.

Someone may be able to suggest a 'product' that may kill the fungus, however it is usually only a short term visual effect as this stuff is like rust, once it is there, you have to cut it out to eradicate it.

DD

Can I retract `ELDERLY COUPLE'???? and put something like....`distinguished and mature couple'???? LOL

The problem is that the mold spreads by spores which can sit for a long time before being activated by moisture,

Under an ideal situation the van would be placed in a sealed plastic bag with operators wearing breathing apparatus to stop the spread.

Many mold spores can be VERY dangerous and can cause many health problems.

Mold health problems

If your van builder has no idea please seek the opinion of a professional mold mitigator.