Preschem FAQ









Preschem FAQ

Preschem has added a lot of new FAQ to this page. To keep them in a logical order, we’ve added categories and grouped them accordingly. To see the FAQ under each category, please click to expand or collapse the FAQ. Then click on the question to see the answer.

Exterior Timber Finishes

Yes, both Aussie Clear and Aussie Clear Light are tinted with “clear” tints. They serve three important functions:

  1. To assist with maintaining the colour of the timber as the oil fades, for a more even and natural look
  2. Restore the natural “as new” timber colour when the natural timber pigments bleed out
  3. Offer the best possible protection against UV weathering

Aussie Clear is tinted to be “transparent” on mid to dark toned timbers, whilst appearing a reddish-orange on light or “blond” timber.

Aussie Clear Light is tinted for light coloured or “blond” hardwood timbers to appear like “wet straw”. Aussie Clear Light can also be used on mid to dark toned hardwood timbers too.

Yes, Aussie Clear and Aussie Clear Light are suitable for all hardwood species and also for Cedar (which is a softwood).

Note that Aussie Clear and Aussie Clear Light have different coloured pigments, so on mid to dark toned hardwoods, either version of Aussie Clear will appear transparent. However, on blond or light coloured hardwoods, the pigment colour will be noticeable. Aussie Clear Light is the colour that most people will prefer on blond coloured timber as the finish will resemble “wet straw” in most instances.

Yes you can! Any of the Aussie Clear versions, or Walnut Timber Finish can be used to treated pine. Be aware that unlike the Exterior Pine Clear, these products all contain pigments, so the pigment colour will be noticeable. The pigment colours are:

  • Aussie Clear – a “transparent” pigment in redish orange
  • Aussie Clear Light – a “transparent” pigment in yellow
  • Aussie Finish Walnut – an “opague” pigment in walnut brown

Lastly, the performance of these products may vary a little from what is expected. This is due to the radiata pine being a relatively low density and porous timber.

Exteroir Pine Clear is not recommended for use on denser and less pourus hardwoods like Merbau or Spotted Gum. If you with to use a finish without a pigment we recommend that you use Radial Timber Sealer.

Do note though that without a pigment, the timber will go visably grey over time. The pigments act as UV agent, so it’s alittle big like sunscreen for timber. If you don’t want it to go grey, then use Aussie clear or Ausie Clear Light.

Weathered timber has turned grey due to the sun. Preshcem has done a news article that discusses why timber changes colour. But belive it or not, badly weather timber can look like new with a little bit of elbow grease with proper preperation, followed by a coat of Aussie Clear or Aussie Clear Light.

Preschem recommends that for heavy weathering, a light sand is the best option. There are some seriously good gadgets out there now such as the Terrassen Blitz, which makes light work of this and removes most of the weathering without having to recess screws or nails. The Blitz is availbable for rent from Woodcrete Pty Ltd in Mulgrave Victoria. If you don’t have access to this, then you could use a regular old sander.

Once you’ve sanded the deck, to make sure all the weathering has been dealt with, use Preschem’s Grey Deck Cleaner as the final stage. This will ensure that you get an excellent result once you’ve applied one of the Aussie Clear products.

This list is a complete and cost friendly starting point, on the bare bones equipment you’ll need to maintain your deck.

  • Grey Deck Cleaner to wash your deck
  • 15-20lt general purpose bucket for the Grey Deck Cleaner
  • Trigger hose or pressure cleaner (with car wash nozzle)
  • Unipro decking kit (this complete kit contains everything you’ll need to prepare and oil your deck, if you don’t have anything in your garage or shed)
  • Aussie Clear or Aussie Clear Light
  • Mineral Turps for cleanup
  • Clean dry rag

DIY Timber Preservatives

Remove the source of moisture. Moisture will degrade timber and the Preschem preservative system applied over time. If the source of moisture is removed, then Preschem products will remain in the timber almost indefinitely waiting to protect the timber when moisture becomes an issue again. Sealing the timber with a quality paint is the simplest and most effective means of controlling moisture in timber when its above ground.

This is subject the the environment the timber is in and how much persistent moisture is present, but for most normal situations where the preservative is expsoed to the weather unless otherwise stipulated:

Timber Preserver: 4-5 years
No-Rot: 4-6 years
No-Rot Gel: 4-5 years (note that exposed exterior timber must be sealed with a quality exterior paint, otherwise the expected life will be 6-8 months)
Clear Wood Preservative: 12 months
Heavy Oil Preservative: 4-5 years
In-Ground Paste: 4-5 years

Preschem’s timber preservative products will kill, prevent and control rot within reason, but will not restore strength. Badly decayed structural timber must be replaced by a registered professional tradesman.

No-Rot Gel

Yes. For best results allow the preservative to dry for as minimum of 24 hours. Use can then use a “builders bog” type filler and quality oil based primer then your choice of quality exterior oil or acrylic top coat.

Timber Preserver:

Yes, but with caution. Timber Preserver’s active ingredeint, Copper Naphthenate, is also used as a paint drier in oil based paints. As such it can be prone to colour bleed. To paint over Timber preserver we recommend the following:

  • Allow at least 2 weeks to dry. Preferably more if practicable.
  • Use a quality stain block type acrylic primer such as those made by Zinsser or Dulux
  • If colour bleed through occurs with the primer, do not continue painting. Strip back the primer to bare timber and allow a further 2-3 weeks to dry.

No. Heavy Oil Preservative contains a medium paraffin oil, making it amost impossible to paint over.

Timber Issues

No-Rot and No-Rot Gel have a very limited ability to control termites, while Timber Preserver has no ability to do so. If you find termites in your home, then the only safe course of action is to contact a registered pest controller who specialises in termite infestation. They will be able to asses the damage done and a course of action to eradicate the termite nest.

Category: Timber Issues

In this situation, you have what is known as sapstain or bluestain mould. While this won’t do a lot of damage to timber, it may visually mask the onset of decay. The best way to determine if there’s rot is:

  1. to probe the timber with a flat head screwdriver. If the tip sinks in easily, you have rot.
  2. If the first test is positive, smell of the timber. If it smells a little like mushrooms, then it might be rotting.
  3. hit the timber with a hammer. if it sounds solid then it’s fine. If it sounds dull, then it could be rotting.
  4. drill one or two small holes in an area you think are suspect and capture the shavings.
    1. notice the resistance on the bit when drilling. rot is very easy to drill through
    2. notice the colour the shavings are. if its dark brown and its a blond timber, then its indicating rot
    3. smell the shavings and if it smells like mushrooms then it’s rot.
    4. rub the shavings between your fingers. if the shavings crumble then its rot

If you have ticked off a lot of positives from the tests above then it can become quite tricky to determine what course of action you need to take. If you have rot in the sub-frame or stumps, then you’ll need to call an expert such as a licensed builder. If you’re still unsure and you’ve had one or two indicators that there is rot above, call in the builder.

After you or a builder have established that the timber is not badly effected, or you’ve had to conduct repairs and replacement, and you want to treat the timber to prevent rot in the future:

  1. Check and improve ventilation under the house. Often the vents are cloged with plants or soil
  2. See if there is evidence of a leaking pipe, as that is a comon cause of dampness under the floor
  3. Apply No Rot Gel to prevent rot from spreading or re-occuring.
Category: Timber Issues

Preschem has discussed borer treatments and their life cycle in this news post on the website. Unfortunately, once you have noticed the pin holes and dust/fras, the adult beetle has emerged from the wood and done its damage. But here are the things you can do to try and prevent further damage.

  1. Photograph the holes to assist you in identifying new borer activity
  2. Treat the timber with either Clear Wood Preservative or No-Rot Gel
  3. Monitor the timber for signs of new holes for 2-3 months afterwoods and retreat if necessary

To figure out which product is suitable for your situation, then:

  • If the timber is sealed with a varnish or paint or is external and exposed to the weather, use Clear Wood Preservative. Note: Clear Wood Preservative can be flooded into the pin holes with a small needless syringe, It can even blown in with a hear dryer (use the fan only, no heat)
  • If the timber is raw and internal, use No-Rot Gel
Category: Timber Issues

Timber Pole Preservative FAQ

Yes, you can use both Polesaver and Bioguard to preserve your timber poles where they’re in contact with the ground contact. You don’t need a special license to apply these products. And the application technique is exactly the same as on the Technical Data Sheets located on our download page.

Remember that for Polesaver, if your poles are under 300mm diameter then you’ll need to use the PS10 (10mm dia) rod with a 12-13mm treatment hole. Or the PS14 (14mm dia) Polesaver rods for poles over 300mm diameter.

The fungi that cause timber decay need three things to live and grow:

  1. Food source, being the wood itself
  2. Oxygen
  3. Moisture (wood has to have a moisture content of =>20%)

What you are finding is that the poles that are weather exposed are geting wet and retaining moisture, especially in ground contact. But the internal poles are not getting wet. As they’re not getting wet, they wont rot. This is where Polesaver Rods and Bioguard Bandage can help you by significantly extending the life of your poles as part of a routine maintenance strategy.

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