How to clean low-e glass (and actually succeed)

Check out our tried and tested 8 step method how to clean your low e glass.

I love this old Gary Larson cartoon. I have it on a mug, which I keep in my bedroom. It’s not for drinking from – I keep it as a reminder of an important life lesson:

No matter how smart we are, things can appear impossible if we are doing things that just don’t work. When something isn’t working, it’s better to look around for new information and change what we do rather than conclude that the task is impossible.

If you go to product review websites and see what people have to say about low-e (low emissivity) glass, you will quickly find a stream of extremely frustrated – even outraged – people. People who think that their glass is impossible to clean.

“Do not ever put this glass in your home”, says one person, “its uncleanable” says another.

Someone even writes: “I am willing to have my house used as a display home by other glass company’s [sic], as an example of Viridians “below standard of product” [sic] and to encourage others to spend your hard earned money elsewhere.”

Ouch! When I first noticed these kinds of comments I was a bit worried.

After all, I recommend this glass almost every day, and have done for the last six years.

But having seen it installed in hundreds, if not thousands, of windows, and having had only positive feedback from customers, I was comfortable enough in recommending it.

Then, last week, a customer called me to say she had tried and tried and tried to clean her new glass, and was really concerned that those reviews might have been right. I immediately arranged to go around and investigate the situation. I knew I couldn’t be happy continuing to recommend this glass unless I could see this difficult situation first hand – and resolve it successfully.

I’m pleased to say that I did resolve it. And in the process I realised how and why some people have persistent difficulties cleaning it. So I’m here to share my insider secrets with you, so you can enjoy your glass.

How is low-e glass different from regular glass?

Low-emissivity glass (also called low-e, e-tech, Energy Tech, Comfort Plus or Comfort Hush) differs from plain glass in that it has a very thin metallic coating on one side.

It is not necessarily tinted – it is usually clear. But it does have a subtly visible reflective quality compared to regular glass. It’s that same reflective quality that bounces the heat back into your house, or keeps it out. One of the features of this difference is that under very particular light conditions, you can more easily see finger prints and streaks on the glass.

This means you are more likely to want to clean it. And if your cleaning efforts don’t work, you are more likely to be frustrated. But there’s another thing that can make it frustrating. You will only see the finger prints from certain angles at certain times under certain light conditions.

So you might wonder if you are imagining things. You might wipe the glass, think you have succeeded, and the next day things might look even worse! So, if you can’t get the glass clean, it can feel like a form of psychological torture. Don’t worry. You can get the glass clean.

Here’s what works:  

General principles
  • Refer to the glass manufacturer’s care instructions for recommended cleaning solutions. This article is based on Viridian’s care instructions because that’s the glass we supply
  • The inside surface of the glass is where the coating is – the outside can be cleaned the same way as any other glass
  • Remove jewelry from your hands and wrists so you don’t risk scratching the coating when cleaning
  • Never use razor blades or metal scrapers or any other metal object for cleaning
  • Do not use any cleaning agents that are not specifically recommended by the glass manufacturer. Ammonia-based and alcohol-based cleaners are always a bad idea with this type of glass. Do not be fooled – just because this particular kind of Windex is good to use it does NOT mean that EVERY Windex product is suitable.
  • Test your approach on one pane of glass and check that it works before you try applying a new approach to your whole house.
  • Clean a whole pane of glass at a time
  • Use lint-free cloths
  • Do not use squeegees to dry the glass because they will leave streaks.

Different cleaning agents work differently. Don’t decide that you can’t clean your glass until you have used the EXACT cleaning agents recommended by the glass manufacturer. If you’re in Australia, this is the product recommended by Viridian.

Methylated spirits can sometimes work well as a spot cleaner, or in cases where the Windex in the other picture doesn’t work.

Cleaning Procedure

Everyone knows how to clean glass, right? But remember the kid in the Larson cartoon – reading and following these instructions could be the difference between simple success and years of frustration.  

  1. Take two clean microfibre cloths
  2. Make one cloth WET (not DAMP) with the exact Windex product that is pictured above. Do not be tempted to substitute with a different product, even if it says it is suitable for glass
  3. Gently wipe the wet cloth over the entire pane. Remember the cleaning fluid is what is doing the work. You don’t need to do a lot of rubbing
  4. You want the glass to be properly wet with the cleaning fluid. Get as much of the fluid onto the glass as you can without it dripping off
  5. Keep the glass wet like that for 30-60 seconds by continuing to wipe the wet cloth over the pane. Keep adding more cleaning fluid to keep the surface wet. If you see bits of the glass drying off, you are not using enough fluid. Your job is to keep that pane wet for 30-60 seconds. You want to give the dirt time to dissolve into the cleaning fluid. Therefore you might find it easier to do this when it is NOT the middle of a summer day in direct sunlight!
  6. Now take your other clean, dry microfibre cloth, and dry the pane off quickly and thoroughly. Do not leave fluid on the glass to dry by itself. Wipe the glass with the dry cloth until it is completely dry.
  7. If you have accumulated a lot of fingerprints already, you might need to repeat this procedure a couple of times to get the desired result. As long as you are seeing an improvement, repeat.
  8. Try methylated spirits if the Windex doesn’t work, and refer to the manufacturer’s instructions if neither of these works

If you would like to talk to a timber window expert who understands all your options, and who will listen to your priorities, then please don’t hesitate to contact us.

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