Question about lining homemade wooden planters

Hi,
I am wanting to build my own, large, planters of found wood and different items and I am wanting to know what are safe materials I can use to line the planters with? I want to start growing my own vegetables but don't care to have wood splinters or whatever else may be in the wood or containers. These would be on my deck and away from growing in a weeded area.

Depends on the project. Are you using lumber, that is, wood that has been milled to specific sizes so it will go together fairly tight? At least tight enough that soil won't fall out.
Or are you using branches or other odd shaped pieces that are more cosmetic, and need a real container?

If the latter, then look into stock watering troughs or feeders. You can drill holes in them for drainage, and to attach the decorative materials. Pond liner might work for this, too, if the irregular pieces can provide enough structure to hold up the pond liner.

If you are using more lumber sorts of materials, and just want to seal them, then there are several ideas:
Most painted on products would be safe, if they are sold for ponds and are labeled safe for fish. (Herco is one company that makes this sort of material, and Mapai is another) They will be quite expensive, though. I would not use ordinary paint, it is not designed for use in constantly wet (or damp) situation, or below grade.

Pond liner is safe, but may hold too much water, and is also very expensive.

Cheaper is to buy the right kind of wood to begin with rather than trying to salvage something that may be toxic, then buying a protective liner of any sort.

Exterior of the wood could be treated in any of several ways, but it could wear off because of water seeping though. Things like clear sealer will stabilize the splinters. I have used the Min-Wax product line for staining then sealing aquarium stands made of rustic wood, and it holds up well. I actually used 3 products- prep, stain then seal one after the other. I also used a similar process on my hardwood floors (different colors, though).

Thank you,
I see have a lot more than I thought to think about. Now I know which direction I need to take.

Thanks,

I have raised beds that are made from nothing more then old barn wood. The man that made them secured the corners but I don't know how to explain what he did. I've been using them for 5 yrs. and while I know they won't last forever they are good now and the only thing I've done to them is plant in them.

I line some of my raised beds with plastic from the heavy plastic bags that compost came in.

Otherwise, water evaporates much too fast from the corners, and even from soil near the edges.

My walls are just concrete paving stones stood on end. It turns out that water or water vapor passes easily through 3/4" or 1" of concrete - or maybe it is the4 cracks between each paver that lets the soil dry out so fast.

I'm with 1lisac,

Simple box sitting on the ground -- no bottom -- no liner...

I made my very first raised beds (RB) from pressure treated (PT) lumber (and, yes, it's perfectly safe to grow veggies in, nowadays...) I bought (ugly word, these days..). I lined the outsides of the boxes with the remaining pickets from my newly installed cedar fence, to match the fence.

These days, I'm making them outta reclaimed lumber from the lumber yard, and anywhere else I can get close to $0 spent. Just cut the usable sections and piece them together. No lining.

Or, once the backyard beautification projects pick up for the summer, I'll get more cedar fence pickets from the culled lumber pile, and make the Ana White $10 raised beds for

Here's my raised bed pictorial.

Great beds! Thank you all for the awesome information! I just may take a trip to the local lumber yard soon :)