Editing Pallet (section)

=== Wood ===
[[File:Crowbar (PSF).jpg|thumb|upright|Wooden pallet being dismantled|alt=A man using a crowbar to dismantle a wooden pallet]]

The production of pallets accounts for 43% of hardwood and 15% of softwood usage in the U.S.<ref>{{Cite journal|last1=Gerber|first1=Nathan|last2=Horvath|first2=Laszlo|last3=Araman|first3=Philip|last4=Gething|first4=Brad|date=7 January 2021|title=Investigation of New and Recovered Wood Shipping Platforms in the United States|url=https://palletfoundation.org/wp-content/uploads/2020/09/BioResources-New-Recovered-Pallets-2020.pdf|journal=BioResources|publication-date=6 March 2020|volume=15| issue = 2|pages=2}}</ref>

The cheapest pallets are made of [[softwood]] and are often considered expendable, to be discarded as trash along with other wrapping elements, at the end of the trip. These pallets are simple stringer pallets, and able to be lifted from two sides.

Slightly more complex, [[hardwood]] block pallets, plastic pallets and metal pallets can be lifted from all four sides.  These costlier pallets usually require a deposit and are returned to the sender or resold as used.  Many "four way" pallets are color-coded according to the loads they can bear, and other attributes. [[Wood]] pallets can pose serious bio-hazard risks as they are susceptible to bacterial and chemical contamination, such as ''[[E. coli]]'' problems in food and produce transportation,{{citation needed|date=October 2019}} and even insect infestation, and thus the need for ISPM 15.

Wooden pallet construction specifications can depend on the pallet's intended use: general, FDA, storage, chemical, export; the expected load weight; type of wood desired: recycled, hard, soft, kiln dried or combo (new and recycled); and even the type of fasteners desired to hold the pallet together: staples or nails.

The price of wooden pallets reached a record high during the [[COVID-19 pandemic]], due to increases in the prices of supplies and labor.<ref>{{Cite news |date=9 April 2021 |title=The Forgotten Shipping Pallet Stages a Pandemic-Era Rally |url=https://www.bloomberg.com/news/articles/2021-04-09/the-forgotten-shipping-pallet-is-staging-a-pandemic-era-rally |newspaper=Bloomberg}}</ref>

Although pallets come in all sizes and configurations, all pallets fall into two very broad categories: "stringer" and "block" pallets.  Various software packages exist to assist the pallet maker in designing an appropriate pallet for a specific load and evaluating wood options to reduce costs. 

Stringer pallets are one of the original models of wooden pallets. They use a frame of three or more parallel pieces of timber (called stringers).  The top deckboards are then affixed to the stringers to create the pallet structure. Stringer pallets can have a notch cut into them allowing "four-way" entry. Forklifts can lift a stringer pallet from all four directions, though lifting by the stringers is more secure. Stringer pallets can be made of both wood and plastic.

Block pallets utilize both parallel and perpendicular stringers to better facilitate efficient handling. A block pallet is also known as a "four-way" pallet, since a pallet-jack may be used from any side to move it.

Carrier blocks are specialized pallets for [[Straddle carrier#Lumber carriers|lumber carriers]]

Flush pallets are pallets with deck boards that are flush with the stringers and stringer boards along the ends and sides of the pallet.{{citation needed|date=October 2019}}

All stringer and some block pallets have "unidirectional bases", i.e. bottom boards oriented in one direction. While automated handling equipment can be designed for this, often it can operate faster and more effectively if the bottom edges of a pallet have bottom boards oriented in both directions. For example, it may not need to turn a pallet to rack it, and operation is less sensitive to pallet orientation.

The least expensive way to improve a pallet is usually to specify better nails. With non-wood pallets, a controlled coefficient of friction is often helpful to prevent the pallet from slipping from forks and racks. Stiffer pallets are more durable, and are handled more easily by automated equipment. If a pallet does not need to be lifted from all four sides, two-way pallets with unnotched stringers may be used, with the additional benefits of added rigidity and strength. Specifying tolerances on flatness and water content may help the supplier meet target requirements. Inspection of pallets, whether in person or by a third-party (such as "SPEQ" inspected pallets) offer additional assurance of quality.

The main processes that are used to manufacture wooden pallets:{{citation needed|date=September 2020}}

* Material selection
* Cutting wood plate / block
* Chamfering (depends on the demand)
* Notching
* Nailing wooden pallet

[[File:IPPC standard.png|thumb|IPPC marks on a pallet from Germany (DE)|alt=Refer to caption]]
[[File:Wooden pallet - TAG ID - palette bois de manutention - Alain Van den Hende - licence CC40 - SAM 2741.jpg|thumb|IPPC marks on a pallet from Germany (DE)|alt=Refer to caption]]

Due to the [[International Plant Protection Convention]] (abbreviated IPPC), most pallets shipped across national borders must be made of materials that are incapable of being a carrier of [[invasive species]] of [[insects]] and [[plant disease]]s. The standards for these pallets are specified in [[ISPM 15]].

Pallets made of raw, untreated wood are not compliant with ISPM 15. To be compliant the pallets (or other wood packaging material) must meet debarked standards,<ref>{{cite web|url=http://www.tcrllc.com/ispm_15_bark_restriction_debarked_bark_free_clarification.html|title=ISPM 15 WPM Clarification |publisher=Timber Creek|access-date=1 September 2016|archive-date=3 March 2016|archive-url=https://web.archive.org/web/20160303202445/http://www.tcrllc.com/ispm_15_bark_restriction_debarked_bark_free_clarification.html|url-status=dead}}</ref> and must be treated by either of the following means under the supervision of an approved agency:

* [[Wood preservation#Heat treatments|Heat treatment]]: The wood must be heated to achieve a minimum core temperature of {{convert|56|°C}} for at least 30 minutes. Pallets treated using this method bear the initials '''HT''' near the IPPC logo.
* [[Fumigation|Chemical fumigation]]: The wood must be fumigated with [[methyl bromide]]. Pallets treated using this method bear the initials '''MB''' near the IPPC logo. From 19 March 2010 the use of methyl bromide as a treatment according to ISPM15 has been banned within all EU member states.<ref>European Commission, [https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32008D0753 Commission Decision of 18 September 2008 concerning the non-inclusion of methyl bromide in Annex I to Council Directive 91/414/EEC and the withdrawal of authorisations for plant protection products containing that substance], 2008/753/EC, accessed 31 October 2019</ref> This is due to causing potential harm to the Earth's stratospheric [[ozone layer]].

Treated wood pallets must be stamped on two opposite sides, indicating either HT for heat treated or MB for methyl bromide treatment.

Pallets made of non-wood materials such as [[steel]], [[aluminum]], [[plastic]], or [[engineered wood]] products, such as [[plywood]], [[oriented strand board]], or [[corrugated fiberboard]] do not need IPPC approval, and are considered to be exempt from ISPM 15 regulations.