I just thought of this today when my 4 year old son pointed out to me that all of the picnic tables in the park were red. I knew it to be true, but as always I must know WHY. Any thoughts?
They are? I never noticed any particular trend in painting those things. I would imagine picnic tables are painted whatever color withstands weather the best.
Are you referring to wooden ones? Most places have metal or plastic ones now.
Many were once made of redwood, but now I see a lot of synthetics are being used. That’s probably a good thing.
I have never actually seen ared picnic table in my life, most of the ones I’ve seen are dark brown (wood) or light brown (varnished, better wood)
So they can be spotted?
http://www.picnicfun.com/picnicking/redwood_picnic_tables.htm
Speaks for itself. 
Do redwoods grow in the UK?
My expertise on trees in the UK is somewhat limited.
(we build things with bricks. Sometimes famous bricks. Like the hardest bricks in the world - nori bricks. Made in my home town of Accrington Lancashire, where I spent the first 21 years of my life. so there. My town is famous for bricks. Wowee)
We make bar-b-ques outta bricks. Wood doesn’t work so good.
We buy metal BBQs. (we’re poor, we make do with backyards, and houses stuck together)
My current house seems to be made out of sand and pebbles.
Perhaps it’s a similar reason like why barns are red. Often red paint was used because the primary component of red paint, ferrous oxide, was inexpensive.
Or maybe it is because many tables are made from redwood and people associated red wood with picnic tables.
I am obviously refering to the older wooden picnic tables, not the synthetic pieces of junk out there today. Redwood seems to be the answer, and the ferrous oxide comment makes a lot of sense as well. Thanks for the insight.
Hmm. What are they made of/are they painted/where are they?
I’ve heard barns are traditionally painted red because iron oxide was cheap and inhibited mold. Perhaps this same theory applies.
All the picnic tables in gov’t run parks here in Alberta are painted official-gov’t-workproject-brown. Most of the tables around schools are the recycled-drink-box type, which can end up being an odd purple colour. But I’m subscribing to the redwood idea, since all the really nice tables in the river valley use plain varnish.
Incidentally, the reason picnic tables and other outdoor furniture is often made of redwood is that it is naturally insect resistant.
Where I grew up (in Arizona), virtually all the picnic tables I saw were made of concrete. I lived there from 1984-1992, so I’m not sure if that counts as too “recent” for this discussion.
Oh, they were unpainted.