Introduction: Heating Bed Glass Sticking Coat for PLA

For less than 10 € and a short know how training, get a life time lasting solution for heating bed glass sticking.

This sticking coat is:

  • Natural.
  • A renewable material.
  • Very cheap.
  • Reusable eternaly (Seems true, but not checked yet !)
  • Easy to set (and clean, after many prints).
  • Leaving a flat and glossy surface on prints.
  • Free of residues left on prints.
  • Sticking so well that you can't remove your print unless bed cools down.
  • Releasing prints under 35°C.
  • Environment and user friendly, free of chemicals.

This is performed by the use of a natural polymer, called Shellac, on your heating bed glass.

Shellac is produced by an insect, the kerria lacca cochineal. It soften with heat and dissolves in alcohol (among others). It is known by humanity since more than 4000 years. It is used to varnish old and fancy furnitures and music instruments, the first 78 turns records were made out of it, the isolation of electrical wires in coils were first made with it, and I can't quote here all the uses made out of it and are still done nowadays.

"Necessity is mother of invention"

As I was born 30 years BI (Before Internet), and because I've always been a hand worker, modules boards, numerical machines, electronic projects or 3d printers appeared to me as alien stuff... I believed one had to study many years and to be good in math. to enter that world.

Then last year, I entered the next door Fab-Lab, ("SquaregoLab", Perpignan, south of France). Meeting people playing with all theses funy things changed my mind. I then soon dared to buy a cheap 3d printer kit with a large bed, and put a dump scanner glass on it.

The machine was ready to print, but this (*) PLA was not sticking !

Mr Google told me it was a very well known problem, but no blue tape, no glue stick, and not even hair spray at home...And my very first print could not wait, I had to find something within the next ten minutes to enter the new era ! I'm sure you understand what I mean...

The solution came by intuition, out of my dusty workshop, from that old buffer varnish technique also called "french polish" for some people. It took me some time to understand why and how it worked so well at the first time, to be able to renew this at will.

(Here is a good video if you want to learn to buffer varnish on wood)

Here I give you the tricks I've found to get constant good results, and beg your pardon in advance for my english being french :-)

This works for PLA. ( I'm new in 3d printing and I don't even have any ABS roll yet, it could probably work, but I have not tryed)

Step 1: Different Kinds of Shellac !

Depending of what kind of tree the insects lived on, the season, the cleaning, etc, the quality is different.

Globaly, there is 3 qualities. brown, orange, and clear/golden

Among theses, there are 2 other choices: plain, and unwaxed

The shellac I use is the Orange Unwaxed ("fine orange décirée" or "blonde décirée"), the one in the middle on the picture.

It's the most used, at a good price around 24€ /Kg but you just need less than 10 grams...

The brown is too "dry" and breaks too easely, and the Astra, (the golden one on the right) is supposed to work too, I have not tryed, but it is much more expensive and because it has almost no color, you won't feel the thickness of the coat applied on the glass.

So, Orange Unwaxed shellac is a good choice for what we want here...

Shellac origin and production video

You should know where it comes from, the people and the forests you support if you choose to buy shellac.

(Thanks Vijay :-)

Step 2: Things Needed

These are first (and second) choice ingredients.

  • 8g orange shellac unwaxed.
  • 100ml of alcohol from drugstore (or alcohol to burn).
  • 10cm² of linen fabric (thick cotton is ok but could leave fibers in the coat).
  • Few grams of cotton wick ( or tousled cotton rope or thin DIY cotton stripes)

Cabinetmakers, or luthiers, use this to make the famous buffer varnish. It can be an opportunity to visit such a workshop and ask for ingredients that you could not find. But all of this is easy to find ... Don't despair finding that in DIY supermarkets, (in furniture polish area)...

We will also need:

  • A small plastic bottle with a tiny hole under the cap. (because one use only few drops each time).
  • A small plastic or glass pot that can be closed hermeticaly. (fabric with alcohol shoud not dry in it)
  • A new large cutter blade.

And eventually, in a second time, a ceramic scraper to clean your glass after many prints because it's safer than cutter blade for this operation..

Step 3: Let's Prepare the Varnish

First, remove the tiny hole plug from the plastic bottle.(using the edge of the cap)

Pour the 8 grams of shellac into it (with a piece of paper, it's easyer).

Add 100ml of alcohol, put back plug and cap, check it's well closed.

Wait 10 minutes and shake it energicaly (if you don't, the flakes will stick all together to the bottom of the bottle and it will be much longer to dissolve)

Then wait 1 to 3 hours, shake it again , check everything is well dissolved, it's ready !

Step 4: Setting the Buffer

Once compressed, the cotton wick bundle should not be bigger than a walnut nut.

Soak it with the previous shellac preparation and knead it. If you press it, it shoud not lick.

Place it in the middle of the 10 cm² of fabric, close the fabric around the cotton wick.

You shoud see shellac passing slowly through the fabric making an orange spot.

It should be damp, not wet. (otherways, we would use a paintbrush, not a buffer...)

Understand that a new dry buffer fabric needs more preparation to be damp...

Your buffer is ready.

Remember : Shellac or alcohol should always be added to the cotton wick, not on the fabric!

If you don't use it now, put it in the hermetic pot !

As much as possible, it should never dry because it hardens.

If it happends, put a few drops of alcool on it and let it 20min in the closed pot before to knead it !

It will then recover it's softness.

Step 5: Set a First Coat on the Glass.

It's a 10 minutes operation to renew every....15/20 prints maybe...

You may wear gloves or not. Personnaly, I don't. Shellac doesn't stick very long on flexible materials like skin, if you forget about it, it goes by itself from your fingers. At the end, one can clean his nails and hands with alcohol if needed.

Clean the glass with alcohol ( remove grease), and preheat it at 60°C. on your heating bed.

Once heated, remove the glass from your heating bed or not, it's just question of being at ease drawing on 8 shapes with your buffer. Glass has to be warm to catch shellac...

The buffer arrives on the glass like a plane landing. When it touches the glass, it's in movement. Same when it leaves the glass. Otherways, the buffer will stick and leave the mark of the fabric, and fabric fibers eventualy.

By drawing 8 shapes, the buffer never pass by the same area. It leaves a very thin coat behind, of a few microns thick. If it passes by the same area, it removes the previous coat.

Cover your glass of theses movements five or ten times only. If the buffer begins to stick, don't go further.

If you cant remove the glass gloss, your preparation has too much alcohol, put more shellac in it.

Once glass looses its gloss, it's ready.

Put it back on your printer, let it cool down and level your bed properly.

This coat works like a primer. It won't stick anything, not even dust. You can leave it on your printer.

Step 6: Let's Print !

In your slicer, as usual, set the heating bed at 60°C or 50°C even, for a large bed, it saves energy.

Send a print, let the bed heat, and during the nozzle heating, take your buffer out of the pot, caress 1 or 2 times the area where the print will happend, and it's ok. Don't put more than this !

To check if it's ok to print, touch the bed with the back side of your fingers, it's not greasy, more sensible and If you feel it's "in love", I mean if it sticks softly without gluing, like tape, great !...

Watch the first PLA coat to set and everything is now ok , it will stick until the end even with long prints (I've tryed up to 9 hours print).

Once your print is finished, wait for the bed heat to decrease under 35°C and hear this lovely "click" that tells you it doesn't stick anymore. Take your print without any effort...I love it !

Step 7: Before a New Print

Prints leaves a mark on the coat. Especialy after a few prints and buffer caresses.

To always have a clean surface, I pull a large cutter blade to remove any asperity.

This has to be done on a cold bed before to send a print and to add a new sticking caress with your buffer..

The dust removed by the blade can be cached by the cotton wick...And will be reused into the buffer while adding a drop of alcohol.

Proceeding that way, your shellac will never be lost and your print space always flat..

Step 8: Totaly Clean the Glass

By the time, the shellac coat can become too thick, glass becomes brown in the middle and nozzle digs into it.It still works great, but the finish on your print can suffer a bit from that.

It happends because one tends to always put too much caress buffer.

So it has sometimes to be cleaned and renewed, and it is very easy to do.

Just like hoarfrost on your windshield, it's removed using a ceramic scraper on a cool glass.

(on the picture I use the cutter blade, but I don't recommand to do that of course...You could harm yourself)

Keep the shellac removed from the bed, put it back into the bottle, add a few alcohol...It's a closed loop.

I'm using the same material that I've prepared last year...

Warning ! Scraping shellac produces some static electricity, be aware of that disadvantage. This means that this operation should me made out of your 3d printer.

I hope this will be helpfull to many makers, to shellac producers and thanks for having read my very first instructable !


DIY Hacks and How Tos (author)2017-07-29

Great solution. Very clever idea.


Thanks...Do some parts remains unclear?? Maybe some wrong english somewhere??? :-)


For the most part it is really good. Just keep practicing your writing skills and they will improve.

About This Instructable




Bio: Out of Boulle School, wood carver then modelist for design and industry until 3d printer were born ! New in makers world.
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