Log Cabin Treatment Gone Wrong

Winter 2017 (update at bottom of page for Winter 2019)

As I’m writing this it is January 2017 and this is relevant as you read this post.

Occasionally we will receive pictures asking for advice on treatment when something has obviously gone wrong with a log cabin. We can also receive complaints about treatment that has been applied to our log cabins from customers who have used our own treatment or other log cabin treatment we have recommended.

Please see this page for our advice on the treatment of log cabins with our recommended treatments, ours and also others. Please also see this file for a discount from a local company who we highly recommend as do other professionals: Brewers Discount.

When treatment goes wrong

We will receive pictures such as these which do look rather awful and the poor ol’ log cabin is starting to look really sad. We usually receive pictures such as these during the late Autumn and Winter when there is a lot more moisture in the air, more rain of course and snow, generally pretty rubbish weather.

This will be when the treatment that is applied is really tested.

Here’s some examples of what will happen when it all goes wrong and your lovely log cabin starts to get some horrible problems.

Bad staining is forming at the bottom of the cabin.

Bad staining is forming at the bottom of the cabin.

Door trims have started to discolor

Door trims have started to discolor

Discolouration and marking of lower logs

Marking and possible spores forming on the door.

We also get sent pictures such as this which are a bit of a fib, you can see that there was a lot of discolouring before the treatment was applied. Perhaps there was a problem before hand?

A bit of a fib, you can see that the discolouration and marks are present under the treatment.

A bit of a fib, you can see that the discolouration and marks are present under the treatment.

This winter we also received this picture.

A picture of an internal wall sucking up moisture and resulting discolouration.

A picture of an internal wall sucking up the weather and resulting discolouration of the inside of the logs that are still wet. Wood is a sponge unfortunately!

All of the above problems are NOT caused by the treatment, they are ALL caused by:

  • Application of the Treatment
  • Amount of the Treatment used.
  • Depth of treatment applied – Basically the number of coats applied.

Please see this article where I talk about specifically about the depth of treatment and moisture content in a Log Cabin

Treatment Experiment

Every year I expect to get complaints such as the above, we get pictures and very occasionally we get arguments that the treatment has been applied as we advise or the manufacturer has advised.

January 2016 I made an experiment board so I can be sure of my advice and to give examples. Here it is:

Experimental treatment boards.

Experimental treatment boards.

These are my logs I painted and fixed to the side of our Shepherd hut display, in front of this is a veranda to make sure the logs are not in permanent sun light, I was trying to reproduce a sheltered position.

I dated these in January 2016 as a reference and started with no treatment, one coat and all the way up to six coats of treatment. I only used our own supplied treatment which was:

Now a year later this is quite interesting and does show quite clearly what happens with the various coats that have been applied.

Now I can actually see this rather than rely on advice from my own experience, the treatment producers and experts have given me in the past, this is starting to show up where the faults may lie, now I can actually see what is happening and confirming what the faults in a treatment could be:

  • Application of the Treatment – how well and how carefully has it been put on.
  • Amount of the Treatment used.
  • Depth of treatment applied – Basically the number of coats applied.

No Coats

My experiment started with no coats of treatment at all.

No coats of treatment have been applied, this is completely bare wood.

No coats of treatment have been applied, this is completely bare wood.

As expected the wood is discoloured and not looking great. This though is of course not wood rotting – wood does not rot if allowed to dry out naturally. You can see though that some fungal spores are starting to form within the structure.

If you don’t ever treat your cabin you can expect the whole building to look like this. Treatment of log cabins

Completely untreated log cabin.

Completely untreated log cabin. This one is now very old but is still not rotten but it doesn’t look great.

Please see my advice on treating your log cabin, you really don’t want this happening to yours:

Carefree Protectant Timber Treatment

Here’s my experimental board using our Carefree Protectant Treatment

Carefree protection board

Carefree protection treatment board

You can see what happens with one coat of treatment, it simply is not enough. We recommend four coats of this treatment. Actually it only requires two coats but PROPER coats and this is always the problem with a totally clear treatment, you cannot see the damn stuff, you have no idea where you have treated! It was easy for me with a small log as I am pretty sure I coated it correctly.

Please note the ‘one coat treatment’ and compare to the pictures at the top of this post. Similar?

Now look at the ‘two coats’ log, you will still see some discolouration, mainly with the tongue part which has borne most of the weather and maybe also where I was a little thin in my application.

Then again look at the third log, it’s better but finally look at the fourth…. now everything is well covered, we know even on the parts you are missing which is happening with a clear treatment you will be getting at least two proper coats on the log.

This of course doesn’t just apply to our own very clear Carefree treatment but also to other producers of treatment.

A clear treatment, in my experience is the WORST to apply as you cannot see where you have been and that results in problems such as those shown in the pictures above.

Embadecor Timber Stain

Here’s my experimental board using our Embadecor Stain Treatment

Embadecor timber stain experimental board.

Embadecor timber stain experimental board.

A stain or a paint is a lot easier to apply properly as you can see where it is and how you applied it. This has worked very well and I am not seeing anything bad here. But there are big differences between one coat and three coats. Please see the previous articles on advice, three coats will at least give you the depth your require to keep your log cabin from problems and absorption as shown in one of the pictures above.

Embalan Timber Paint

Here’s my experimental board using our Embalam Paint Treatment

I was really pleased with the paint, it went on well, I tried a further experiment one that was as standard:

Embalan standard paint

Embalan standard paint

With one costs you can still see the grain coming through, maybe like one of the ‘fib’ pictures above? Three coats is working well (most paint suppliers will recommend three coats and often include an undercoat) Four and five are perfect!

Then I tried mixing, we wanted a darker colour for the highlight on the doors and window of the Shepherd Hut:

Mix of paints from the Embalan range.

Mix of paints from the Embalan range.

Maybe it was due to the colour but this worked really well, yes there is a difference in the coats, maybe four seems to be the best?

Treatment Recommendations and Problems

With my experiment I think I have shown what happens, I’m going to leave the logs out for another year to see how this develops and follow up in 2018.

My advice …. is …. please follow my advice and avoid some horrible problems happening with your log cabin … oh and don’t cheat or fib ….. the Autumn and Winter will decide how well you have treated your Log Cabin.

Also, please watch out for:

  • Application of the Treatment – how well has your coverage been applied?
  • Amount of the Treatment used – Have you applied the right amount of coats?
  • Depth of treatment applied – Basically the number of coats applied. Have you applied the right amount of coats according to recommendation?
  • MAKE sure you treat the door and window trims and quadrants / beads- These are often missed as it is close to the glass and hard to do and you maybe applying a thinner coat?- Maybe consider removing the glass for better coating.
  • Be careful at the lower levels of the log cabin. These four or five logs get the most weather, treat them accordingly.
  • Be really careful when using a clear treatment to thoroughly cover the log.
  • Pay extra care to lower logs any ledges / tongues.
  • Thoroughly coat the corners and any joins.


I am going to leave the experiment up for another year to see what happens, this is really quite interesting ……

More … I’ve recently been asked about our treatments:  This post relates entirely to the Tuin range of Log Cabin Treatments and clarifies what and how we recommend they are used if you choose to use our range.

UPDATE – Winter 2019

My experiment continues with the treatment boards and it’s still pretty interesting what is happening 3 years on.

My timber treatment experiment which I started in 2016 as a way to see exactly what can happen.

The embalan paint if still performing well. The board right at the bottom received no treatment at all, it’s interesting to see there is no rot whatsoever. We’re proving well that three coats and above is giving the best protection. I’m also proving that timber, when allowed to dry naturally does not generally rot.

I did also start another experiment in August 2017 just to see what will happen to a log in constant ground contact. I’ll come back to this is August 2019 to see what, if anything, has happened.

The mix of Embalan paint is also doing very well, the three to five coats are still almost perfect.

The Embadecor stain is doing the best and even with one coat it is still looking very good. Again thought, three to four coats is performing the best. However, bear in mind a stain is just that, ideally it needs a top coat of a sealant such as the clear embadecor or the carefree to ensure the wood is sealed, especially in the corner and joints.

My favoured treatment is also still doing very well. You can see though that as it is a totally clear treatment it is essential to make sure of coverage. I wish I had painted the ends rather than just the surface as you can see how the weather has pushed in. Again three coats and above is most effective.

What if it has gone wrong?

For an easy solution on how to get the timber clean again before re-treatment please see this post: Cleaning a Log Cabin

Timber – Wood – Log Cabin Cleaner

I’ve been playing a lot today with a new product, I’m still experimenting with it and will produce a blog on it soon.

Here though is my first video on it ….. great for cleaning your timber cladding, your old log cabin or in fact any type of timber as far as I can see so far:

Tuin Log Cabin Treatments

This post will explain the Log Cabin Treatments we offer, but in other posts I talk about the importance of a good quality treatment which is correctly applied in regards to Log Cabins and what happens if it is not done well with the best products or not done at all, these posts are here:

In these posts I gave general advice on treatment but did not specifically or simply talk about our own treatments and what we recommend if you choose to use them. I have had a few comments on the posts regarding this so will now answer this in relation to our own Tuin Timber Treatments and how to use them with your log cabin.

Timber Treatment Types

We have six types of treatment for your log cabin:

Factory Treatment Options

Spray Painted – Undercoat only:

This is ordered at the same time as you order your log cabin, it is an undercoat service only and provides two coats of spray paint, it is best to choose a colour that will compliment your final two top coats after installation. Ideally you will use two coats of Embalan Timber Paint for the two top coats.

Using this service will save you time and also give you some confidence it is protected from the elements straightaway. I do though find this quite expensive and do not always recommend this service as it can delay your log cabin delivery for up to 8 weeks.

This is our Flow Log Cabin and pre spray painted in Grey

Immersion Treatment:

The second of the two factory options of treatment, this, like the spray treatment will also need two further coats of additional treatment once it is installed. This treatment is where the entire log cabin and all its parts are put into a vat of rot proof treatment and allowed to soak for hours. This then allows the wood to absorb the rot proof treatment. It is then separated and allowed to dry naturally. Like the spray treatment this will extend your delivery by several weeks.

Personally I do not really like this treatment in anything other than a Log Cabin Gazebo or a Log Cabin style Garage as everything is treated and in brown, green or silver grey it can make the building very dark inside.

Remember that this is only a rot proof treatment, two further coats of treatment will be needed for it to be protected from the weather and to prevent it absorbing water thereby creating water marks and wild expansion and contraction in the log cabin due to the moisture content in the wood.

The perfect treatment on top of this from our ranges is the Carefree Protectant Timber Treatment. Two coats, well applied, are required for full protection.

An immersion treated cabin in green being installed – I like immersion treatment for Gazebos such as this, I’m not so keen on a full building as it makes it very dark inside.

Log Cabin Treatment Options – Self Applied:

Carefree Protectant Treatment:

This is now the very best selling treatment we offer, it is state of the art and is a simply amazing product, please see the Carefree Protect Timber Treatment page for all the details. I thoroughly recommend this and have been using it on everything from a log cabin to hardwood furniture.

Ideally this is used on it’s own (other than the immersion treatment), no base coats of preservative are required or any other product. For full protection for years we recommend three – four, well applied coats.

It is available in a number of colours and all finishes are slightly satin, the clear is VERY clear which people love. It is expensive but I think it is worth the cost. If you love the wood colour and want it to shine the Clear Carefree is Amazing!

I would not recommend using any other product with this or painting anything on top of it other than more of the Carefree treatment when re-application is needed. Saying that, I am told that you can paint on top with anything but i personally cannot recommend it having not done it myself. I also cannot see any point in this as this is a great treatment on its own.

Carefree timber treatment, 3 – 4 coats are required. These logs are an ongoing experiment of mine from January 2016 showing the effect of different layers.

Embadecor Timber Treatment:

Embadecor Timber Stain can be used on its own if you require a stained coloured finish. Like Carefree no other treatment or preservative is required. Again like all good treatment you will need to apply three – four coats if you are using it on it’s own. Lots of colours of stains are available, please see more details on the Embadecor Timber Stain page. Embadecor treatment should be used as an undercoat for the Embalan Timber Paint.

If you like the stained look whereby there is a colour but with the grain of the wood coming through then I recommend this stain highly (still not as highly as the carefree though)

Embadecor timber stain, 3 – 4 coats are required. These logs are an ongoing experiment of mine from January 2016 showing the effect of different layers of the stain.

Embalan Timber Paint:

This is a very high quality paint in solid colours, it gives great coverage and is available in several colours. This is on par with what I consider to be the best UK paint – Sikkens. To use this successfully it is recommended at least one – two coats of Embadecor timber stain (clear) as the undercoat. Further details of this paint can be found on the Embalan Timber Paint page.

Embalan timber paint, 3 – 4 coats are required if used on its own. These logs are an ongoing experiment of mine from January 2016 showing the effect of different layers of the paint. If you use an undercoat of 2 coats of clear Embadecor stain then two top coats are required of the Embalan paint.

Impregnation Fluid:

If you have a hot tub, a jacuzzi, a freezer or fridge in your log cabin or even if it is being shut up for a long time then it is a good idea to protect the inside of the cabin. The impregnation fluid is excellent for doing this, it is clear and goes on like water and will inhibit the formation of damp spores and guard against fungi / mosses forming. You can paint / stain over this as required. This is only a rot proof treatment and does not guard against the weather. This is also an excellent treatment for timber that is already suffering from not receiving any treatment at all to kill any bugs that may be present before applying a proper treatment outside.

Carefree Timber Cleaner:

I will come back to this as I’m still experimenting with the product. Suffice to say this is a 17 years old building that has NEVER received any treatment at all as an experiment. Now I am looking at how to clean and refurbish it. This was using the new product and took literally a few minutes to achieve. Guess which bit we treated with the timber cleaner?

Picture taken of a 17 years old log cabin which has never ever received any treatment or love in its life. A liberal spray of Carefree Timber Cleaner is doing just that.

A quick test ….. more to come in a blog post and product launch.

Log Cabin Treatment Summary

I’ll give a quick run through of my recommendations and combinations of treatments using Tuindeco range to sum up.

  • Spray undercoat – TWO further coats of treatment will be required using Embalan timber Paint.
  • Immersion Treatment – TWO further coats of treatment will be required, these can either be Embadecor Stain or Carefree Protect. I would not recommend the Embalan paint without applying two undercoats of the stain first.
  • Carefree – Only use this on it’s own, nothing else is required, 3 – 4 coats is perfect for 100% protection. No undercoats or topcoats are needed. Just use Carefree and nothing else.
  • Embadecor Stain – 3 – 4 coats gives 100% protection, nothing else is needed. lightly sand between coats.
  • Embalan Paint – 3 – 4 coats is good and can be done so without an undercoat if you wish. BUT, for best results use at least one coat of clear Embadecor stain as an undercoat. For the perfect solution use two coats of clear stain followed by two coats of paint.
  • Impregnation Fluid – Ideally use inside when damp conditions persist – one – two coats.

For my other posts on the treatment of your log cabin timber please see the posts below:

Timber Treatment of Larch / Douglas or Oak timber

This is just a teaser, have a look at this treatment we will shortly be launching:

This is a timber treatment primarily designed for larch and oak or douglas fir. It cleans prior to a proper treatment using something like our Carefree Protect Timber Treatment …. it looks damn impressive!!

I’m wondering if this will work on cleaning up a log cabin if it hasn’t been treated properly or for a long time when a cheap treatment has failed …. interesting …  I will come back with findings soon.

Log Cabin Treatment – Again

I had an interesting question today – “Why don’t you treat a log cabin before delivery as standard like they do with a shed?”

I’ve answered most questions I think in this blog. So far we’ve had:

  1. Depth of Treatment and moisture content in log cabins.
  2. When to treat your log cabin.
  3. Basic terms and what to use for treatment on your log cabin advice.
  4. Cracks and splits in timber we use outside.

But, yes I haven’t yet answered this one, and the simple answer is ‘cos they’re tricky blighters and are not a shed.

A shed is easy, first we make a frame on a bench, pop some cladding on it 12mm thick, nail it on with a nail gun to create a panel. With all the nails in it it’s not going to go anywhere. We can then chuck it in a dip tank for a few minutes or if we’re a posh factory a spray booth and we’ve got a treated shed. Easy! We know as well that nothing is going to happen to it as it’s all really well held together.

A log cabin is slightly more tricky. It doesn’t have a frame, every single log interlocks into each other and we want those connections to be tight and remain tight over the years (Corner connections in log cabins). To do this we kiln dry the timber to a moisture content level commensurate with the country the cabin will be in, generally to around 14% for the UK. We then mill the logs in highly accurate computer controlled machines and out pops a log cabin.

If we then start mucking about with it the logs can all absorb moisture at different levels, this then affects the milling and subsequently the installation as it has been made so precisely. Plus, you spend a lot of money on us providing you beautiful Spruce (Types of timber in log cabins) do you really want someone else to muck about with this? Isn’t it better to treat it how you want to?

We do though offer some treatment options:

You will notice how long the lead time is, this is because we want to make sure everything is properly dried and remains stable for an easy install.

Please also see another post: Log Cabin Treatment Gone Wrong

Treatment of a log cabin – Customer Question

I always try to offer the best advice I can and sometimes, although I recommend our Timber Treatments I do also recommend others to give customers a choice.

A customer wrote to me following our email exchange:

I really appreciate the extra detail as I certainly want to get things right – it’s very good of you to pass on your experience. I have tried to research this online but it’s surprisingly difficult to find good simple advice for a complete novice. A step by step guide “painting a shed for dumb asses” would probably clock up a lot of hits on your site! 😉

I have enough information to make my own decisions now and understand how important the base\DPM and ventilation are.

I’m not going to write such a blog post as suggested for ‘dumb asses’ but it might be useful for you if I copy my email to Mr M that prompted this reply … it does go on a bit but may help with further treatment questions and your understanding of it.

I tend to advise the simplest option – three coats of something expensive. Don’t use ………. on it’s own, especially their shed treatment as it’s terrible for log cabins.

For the first few years of life of a log cabin overkill is a good thing. The wood is kiln dried and I have a personal theory that because it is, the straws that make up wood are still very open, the wood is not really dead as dead should be, it’s an artificial death that we’ve forced on the poor tree.

It’s this openness that allow moisture from the surrounding air content to be absorbed and expelled quickly. Wood is basically made up of loads of straws (needed to suck up moisture from the ground) and it’s these straws we want to bung up. a good few coats of a good treatment does this and there’s never a problem.

Ideally timber should be air dried, But, if we did that you would wait years for your log cabin / table / worktop / kitchen etc and no one wants that.

A cheap treatment won’t stop the transfer of this moisture, there isn’t enough thickness to it to stop the moisture flow. If you use something cheap she will expand and contract a lot in the first year.

Second and third year you will not see it as much, this is because I think the straws have collapsed slightly and / or bunged up. The wood is also more dead and starts to behave more like air dried timber with less movement.

If a building is well ventilated a preserver is not necessary. If a building is not treated at all but is still ventilated it will not come to harm either please see this old girl who has never been treated: https://www.tuin.co.uk/blog/log-cabin-treatment-panic/ (some expected patterns of behaviour though)

Timber treatment and what is recommended by me, the producer, the treatment supplier all have different reasons.

From my point of view I don’t want a complaint from you next year that your building has expanded / contracted and you have a gap somewhere or white bits showing. Of course this is what wood does, it expands and contracts and if a customer understands this it is never a problem, gaps will only appear if it is restricted by a window or door frame being held in place. But your cabin will move quite a bit over the first twelve months.

Sometimes though we see something else: This year we had a problem with one of our show buildings, when the Spring hit, one side contracted quicker than the other due to only one coat of treatment being applied and the sun very, very strong on just one side, the other was in total shade. It meant the straws hadn’t been blocked enough so expelled moisture far quicker than the other side that was shaded. I knew what the problem was and sure enough a week or two later everything was equal and another coat applied and no problems again.

This is why we say 80 – 120 microns depth of coverage, this is also what all the good and expensive treatments will give you. This is why they all say 2 – 3 coats and this is to make sure the depth is thick enough and closes the straws and stops uneven movements.

So, we’ve blocked up the straws which is my consideration and so I don’t have to speak to you next year when you tell me about expansion and I have to explain it and moisture content in the air: https://www.tuin.co.uk/blog/depth-of-treatment-and-moisture-content-in-wood/ and why your cabin is behaving this way.

Next we can move onto the producer both he and I know for certain that wood will never rot if allowed to ventilate. But, we have to account for a dodgy base, water sitting at the base, foliage up against it, insects eating it, bird dropping introducing fungi, no damp proof membrane etc and this is why we will want a preservative. This will stop and inhibit anything forming should a customer be a bit of a numpty and not realise this themselves. This will stop you speaking to me in about 5 years time.

Then we come to the paint / treatment manufacturer – They will be wanting to cover their butt. They will want overkill, belt and braces and will ask you for everything, the same as we should do. If anything happens they will want to ensure you did everything correctly. They also know that wood doesn’t rot if ventilated but also want to watch for the errant customer. If everything is done correctly, no matter what you do to timber it will always be fine. But, if it is exposed to wet and not allowed to ventilated very regular treatment needs to be given.

If all of the above is understood, and the inherent nature of wood is understood such as expansion, contraction, cracking, splitting etc: https://www.tuin.co.uk/blog/cracking-and-splitting-in-timber/ then a good quality treatment is enough, two to three coats applied the building will look good for several years before re-application (mine was using S—— years ago, all I do is pressure wash it yearly, it could do with a touch up but it’s still rot free) If though it is wet constantly then more considerations need to be made to guard against rot caused by damp or infestation.

My advice is good ventilation, a good base and a DPM is the most important thing to give a log cabin a good start in life.

From then on a good treatment of about 2 – 3 coats, ideally something that does it all without under preservatives for ease. Something that looks good and you don’t have to re-do for a couple of years. (our treatments are very good by the way!) Remember what wood does naturally and enjoy it. Bear in mind though as well, one of the reasons why we buy a good treatment for a log cabin is the elasticity, the bloomin’ things move and this elasticity does help a lot especially in the joints over the first year and is very important, cheap treatments will not give you this.

I hope this has helped?

Please also see another post: Log Cabin Treatment Gone Wrong

More … I’ve recently been asked about our treatments:  This post relates entirely to the Tuin range of Log Cabin Treatments and clarifies what and how we recommend they are used if you choose to use our range.

Tanalised / Pressure Treated Garden Timber

Earlier this week we received a review on one of our products, part of it was:

“The first thing I noticed was how badly it had been pressure treated with green splatters on a number of pieces”

I personally really hate a bad review, this was one but unfounded, we try our hardest to provide a top quality product with a top class service and will review everything that is said to improve where we can.Sometimes though it just comes down to understanding a product that you are buying and the expectations that match it.

This review has prompted me to write this quick post as from this statement it is clear that customers are not realising what tanalised timber actually is: I shall explain a little about it so people can gain more understanding of what you are buying and that there are no faults at all nor “badly” carried out.

Tanalisation / Pressure treatment are one of the same, it is the identical process and is carried out normally on pine timber for outside use as a rot protection:


The two terms used are describing exactly the same timber treatment:

  • Tanalised is actually a trademark, as is ‘Tanalith E’ which you will see sometimes.  This brand has been around since the 1940’s.
  • Pressure treatment is the process carried out using ‘Tanalith E’ or similar.


The treatment process is carried out by placing the timber in a big tank.  The door is shut and a vacuum is created inside it.  Then the pressure treatment fluid is allowed to enter and is forced in the wood under the pressure.  It penetrates to a depth of a few millimeters.

Pressure Treatment process using 'tanalith' or similar


The main ingredient is copper with other chemicals added.  Copper is excellent for protection against rot and insects.  The other chemicals (Biocides) protect against other rot that the copper can’t such as ‘brown rot fungi’.  These substances are not harmful at all and can be used around animals and children.  Fish may be sensitive to it.

Rot Proofing of Timber 

It does exactly what it says and protects the timber from rot really well, internally they say about 60 years and externally about 30 years against any form of rot.  It’s pretty good stuff!

Promotional video explaining the Tanalisation process / Pressure Treatment

Please note after watching the process, it is in a huge tank under a vacuum, it cannot be at fault or ‘Badly’ done.

Limitations of tanalisation / Pressure Treatment

So now we understand how the process works, as the video explains, the timber will be:

  • An initial light green colour.
  • Weathers to a light honey brown.
  • Eventually to a natural silver grey.

This change of colour is not any indication of loss of preservative protection. Subsequent decorative finishes can be added to create the look you desire, you will see many examples of this across our website and catalogue.

We supply fixings that will have a comparable life to the timber for many of our products but please note if timber is cut, notched, sawn etc then a comparable treatment will need to be applied to carry on protecting the timber.

Perceived Faults in Pressure Treated / Tanalised Timber

Occasionally, a customer will perceive faults in the process without a full understand of it such as the above review. Some of these perceived faults are:

Formation of salts: 

With impregnated wood it may seem as if salts are formed on the surface of wood. It is actually resin that colours yellow/green due to the impregnation. These stains will vanish in time. This is an example and shows the ‘Splatters’ complained about in the review:

One of our fence panels displaying the formation of salts and "Splatters"

One of our fence panels displaying the formation of salts and “Splatters”

You can see from this picture green portions on the fence panel. This cannot be helped and is part of the pressure treatment process. You may see this on your new pergola, planter or gazebo, please expect this, it is completely normal.

Fungi and blue moulds:
Wood impregnated by boiler pressure induction will become very humid while being processed. As a result, the wood can be affected by mildew and fungi, especially during the warm seasons. These visual imperfections of the product will vanish or can otherwise easily be removed by hand.  Fungi do not affect the quality or strength of the wood.  Since wood can swell and shrink as a natural product, the dimensions listed in the catalogue and product pages can show small deviations.
This is an example from one of our show buildings. You can also see a small split in the timber which is also completely normal (more information: Splits in Timber is normal)
Blue mold and the formation of salt crystals.

Blue mold and the formation of salt crystals.

 All of these blooms, stains, salts etc can either be washed off or left, they will eventually go and is a standard feature of any timber that has been pressure treated. Our customer with the bad review went on to say:
“The pergola is up now and after fixing it and rubbing down the green splashes”
This was extremely worrying and I have advised him since, but, please do not “rub down” the ‘Splashes’! Doing so will remove the protection. Removal of resin bubbles is fine with a sharp knife but do not rub down the surface.
As we have learnt these are not a splash, these are the inherent properties of timber and the tanalisation process and are the cause of the copper ingredient reacting with the moisture and sap within the timber itself.
Here’s another example of a perceived fault:
Light bleaching after the tanalisation process.

Light bleaching after the tanalisation process.

I have added green lines on his product to highlight it more for you. You will notice there are some lighter lines. These lines will have been caused after the pressure treatment process and during storage. Light affects timber, it cannot be helped.
During storage certain parts may be covered due to packaging, positioning etc. Other parts are exposed to light. Light will start to react with the timber turning it first to brown and then to a silvery colour. Again this cannot be helped and should be expected.
After a few weeks all of the new structure will reach the same colour due to light exposure.
Of course you can add your own preferred colour to any tanalised timber. Tanalisation / Pressure treatment is of course only a rot proofing treatment is is NOT a decorative or weatherproof finish. Further treatment is highly recommended to stop cracks and splits, prevent warping and to maintain its good looks