Wood Preservatives

From DIYWiki
Revision as of 20:50, 25 March 2008 by (talk) (orbocrelb)
Jump to navigation Jump to search

focus group batman begins batmobile mcgregor iowa realestate benson carabiner free ebony porn movie clips newsbin pro cracks hermetic sealing service systems would contractions medication orange county web design online address book hot girls costa maya property www web electric deep fryer scented gel candles selvages http home rea wire pugle dog picture www pomerainian custom fabric pressure canner hollywood sign lou and andy older woman venice map people in dance 3 millionare spot ways definitive technology page top marc edouard vlasic acai berry sea lion mating mexican embassy california mysteries home myboylinks www.webstakes.com saddle packs randi storm morphine pulse transformer tutorial boulders real estate embajada de canada en caracas website hitachi projector jag spoilerfix the cut exercise equipment for spinal injuries tierrasanta rec center digital motion control www.kayak.com madhouse studio birmingham beyblade priya arcsinus http apartment elmwood nj park rental extended rv warranty internment camps patriotic wallpaper montgomery gi bill tune 1000 nintendo revolution www what would you do city high nfl watches http easy music quintet woodwind management resume samples stallion mounting behavior olsen twins thong asthma meds designer shoes for less pernod absinthe raw 2 game www job performance assessment lahontan valley press solar electricity provider polaroid film recorder vertec mens perfume egyptian myths uterus office telephone system business gift plus size intimate appearal horse grooming supplies schonbek crystal chandeliers link line6 bundles canon 5d prostar physical fitness in ancient rome ecw francine buy darvon megan fox arena custom entry doors intuitive web e learning centres guide to e learning nicole kidman oops ejazz lines masala zone upper street freewill astrology barn doors hunk religious pictures webmap naaa nickname generator sponges phylum universal clays best gas mileage adult character child development in webmap torcher respect teaching sorrento tourist wedding dresses st paul evergreen cemetery louisville kentucky razoos dallas illustrated properties james bond fancy dress hire 30 ford model a the king ski doo cowboy clip art elevated dog bowls revolution for cats sheer clothing shaw hardwood floors add remove programs not working used office furniture dealer internet browser windows free peeing women wind power energy source stan marsh sklavin unterwerfung jetskis ritmo consolidated credit counseling services telus idol map ecce romani latin book stephen king the long walk mini portable air conditioners vancouver washington fingerd deestylistic mazda 6 wagon pics sky harbor airport lcd hdtv arthur grossman bassoon tanja jess body mass index calculator civil investigations how to clean pet urine online drugstores more material testing gun cabinets burke domai artisoft phone systems product survey form index equipamientos ferroviarios home inspection service motor neurone disease research inuyasha and kagome making love kombat mortal rom snes domain maui condominium home high potency hgh spray static magazine victoria bare midriff 10 ps santana se vende teresa may rwanda zero turn mower review king of rock and roll woodlands inn fort nelson airvac valley stream station extreme 4x4 hosting solution msnbc news world ethanol production yamaha motorcycle commercials yearbook quotes types of bees Most exterior woodwork needs treatment to prevent or delay rot. The main treatment options are given.


Water based Preservative

Water based preservatives have become popular due to lower cost per gallon. However this is only part of the story.

Water based preservatives have a very short life, and typically need recoating every year. This means an annual travel to the diy store, money spent, and time spent recoating the woodwork.

They are also not as effective as spirit based products, and will not effectively prevent rot in wood constantly exposed to water, such as fence post bottoms and earth retaining woodwork (eg bed edging, raised beds, compost containers).

Spirit based Preservative

Spirit based preservatives last multiple years from a single coating. This makes spirit based preservatives a much lower cost option than water based, even though the cost per gallon is higher.

This also makes spirit preservatives the more energy efficient option. Although the per gallon energy input is higher, many less gallons are used, due to less frequent application. Less transport & human travel is also needed, further reducing energy consumption. The reduced frequency of painting also means much less human time & energy input.

Oil based Preservatives

Used engine oil mixed 50/50 with paraffin or diesel has long been used as a wood preservative. It is very effective, but there are now concerns about the possible toxicity of contaminants in used engine oil.

New engine oil does not contain engine contaminants, and a new oil & paraffin mix will be discussed here.

  • Fully effective
  • Long lasting - many years
  • Low cost - typically around £3-4/gallon retail
  • Safe to handle
  • Preserves wood in constant contact with wet earth


There are 3 drawbacks, all of which are temporary, and disappear in the days following application.

Temporary Oiliness When initially applied it creates an oily surface. Within a day this soaks into the wood, leaving a dry surface.

Flammability concerns Like any spirit based product, an oil & paraffin mix is flammable. However it can not be readily ignited like petrol. Neither diesel nor engine oil will ignite when a naked flame is applied, and nor does a paraffin & oil mix. Paraffin is more flammable than diesel, but quickly soaks in then gradually evaporates away. Wood so treated does not become an increased fire risk, the prime problem is public perception.

Whiff Paraffin creates a very mild whiff as it evaporates. This is temporary & harmless, though it lasts for many days. This makes it ill suited to indoor use.


The paraffin can be substituted with diesel, kerosene or heating oil, but not with white spirit or petrol. White spirit is not effective, and petrol is dangerously flammable & toxic.

Don't use engine oil alone. Some oils soak in well, but engine oil sometimes does and sometimes doesn't.


  • Alkyd oil paints (household gloss paint) last a few years
  • Keeps water off wood, but does not provide any anti-rot chemicals to the wood.
  • Different chemistry to oil based preservatives.


Stockhom tar is smoked cooked pine resin. Tar waterproofs as well as preserves, and is thus a good choice for the bottom underground sections of wooden fence posts, and the ends of joists where inserted into masonry.

Expert article on Tar

Liquid asphalt

A sprayable diluted asphalt.


Tung oil, danish oil, boiled linseed oil etc


Creosote is the most effective and long lasting wood preservative of all. However it has downsides:

  • Smelly, almost stinky
  • Filthy
  • Permanently stains clothes, carpets, paving etc
  • Toxic
  • The fumes from application kill most plants within a radius of many feet.
  • Smell & plant deaths can lead to neighbour disputes
  • Now banned for home use.
  • May be legally applied by professionals
  • Available from trade outlets, but not DIY sheds

Application Tips

Thirsty Ends

Cut ends of wood are the most vulnerable to rot due to higher porosity. Repeated coating or preferably soaking in preservative can extend life.


The more preservative you can get into the wood the longer it lasts. Soaking wood in presrvative is therefore common. This can be done with a large container, or by standing the cut ends of wood in a bucket of preservative.

It can also be done by wrapping polythene sheet under the wood, supporting all the edges above the top of the wood, and filling with preservative. This minimises container volume, and is good where a minimal quantity of wood needs treatment. Before use check your preservative does not melt the polythene.

Dust sheets

Preservatives stain paving, so dust sheets are useful. Newspaper absorbs spilt preservatives and helps reduce spread due to treading. Waterbased stains are the least problematic in this respect, as the stain soon fades and disappears.

Indoor use

Use of non-water based stains indoors may in some cases produce concentration of fumes high enough to be an immediate risk to health. Check the label.

Durable Woods

Some woods don't need preservatives for outdoor use. These include:

  • Oak

See Also