Packing framed pictures in plywood to send by post.

[Not your average framer]

How solid is 4mm plywood for posting framed and glazed pictures by post? Also want the best intenal package materials? I want to ensure that these framed pictures arrive intact. One side piece of plywood will be removable to open the package to unscrew fixing screws with a screwdrver.

Thanks,
Mark.

[JFeig]

Properly secured plywood will be fine. The thickness is dependent on the outside dimensions.
Per FedEx, DHL, UPS, etc. there has to be sufficient internal padding to cushion the internal contents. This is usually stated in the 50mm range on all 6 sides.
My favorite padding is 1"-2" Styrofoam insulation sheets or a corrugated cardboard structure that suspends the contents away from the sides.

[Not your average framer]

Thanks Jerome,

I've got a good stock of about 5mm double thick, double corrigatied cardboard, which I can layer together to make up the necessary thickness. I bought quite a lot of it about two years ago and have not had much chance to use it so far. I like to glue bits together with the flutes in different layers in opposing directions, which seems to be surprisingly stiff, if you have a few layers.

I can buy 3ft by 4ft sheets of 2mm thick MDF, from a franing suppler at quite a good price instead of using 4mm plywood and perhaps rely upon the layers of corrigated cardboard to support and stiffen the 2mm MDF outer skin of the box. Maybe, this might be adequate for smaller items. I'm still thinking about that possibility and I might build a test box to see how well it works.

The test box would need to be subjected to some kind of severe testing to see if the contents survives some excessively severe treatment, without any actually damage. Throwing a packed frame in a box dow a flight of stairs, might be quite a good test, if it bounces onto some of the stair as it goes down. I will be wanting to ensure that the glass does not get broken! I will probably need to dampen any severe vibration from damaging the glass.