Geert Keteleer's Salt Water build-plate adhesion...amazing!

[nzo 16]

I decided to try Geert's salt-water method today and was blown away. A thin, hardly visible layer of salt on the glass plate created trouble-free adhesion. When cool, the prints simply pop off with light pressure.

No fuss, no mess. I could not believe it until I had printed 3 of Geert's "snake" clamps for the UM2+ feeder tube and wiring loom. No pressure on the feeder tube, just support.

Thank you Geert

If you're interested you can get details here. Grab the info while you can.

Edited July 18, 2017 by Guest

[prb4 6]

I'm interested, I've read Geert's original post, but I have questions?

(The link you provided doesn't work for me)

How do you actually lay down the layer of salt?

Do you dip the glass bed in a bucket of salt water?

Do you dip a cloth in the salt water and dampen the glass bed?

Or is there another way?

Thanks

Peter

P.S. I find glue stick generally works for me, but not always, so I would like to try this method if possible.

[geert_2 557]

I am glad the salt method works for you too.

@prb4: try this link: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/

First thoroughly clean the glass, and then clean again with plain warm tap water only (no soaps, no window cleaners). This outside of the printer, of course.

Then I just put a few drops of salt water on a paper tissue, and gently wipe the glass plate. Gently keep wiping while the water evaporates. So it leaves a thin mist of salt stuck to the glass, nice and equally distributed, but almost invisible. It looks like the glass is just a bit dusty.

On the second application, I just redo the wiping in the printer, without prior cleaning, and without taking the glass out.

The disadvantage: you have to wait until the models cool down, to get them off. And it requires a heated build plate.

For me this works very well for Ultimaker and colorFabb PLA, and a bit less but still okay for ICE PLA. But it does not work at all for ABS. For PET it works a little bit, but less than dilluted white wood glue (gr5's receipt: ca. 1 part glue in 10 parts water).

If you try other materials, let us know the results (or the lack of).

[nzo 16]

(The link you provided doesn't work for me)

Sorry Peter, I screwed up the HTML link code. Works now...HERE

Edited July 18, 2017 by Guest

[nzo 16]

Nice to see you here Geert!

Yes, so far PLA only.

The salt is only a very thin layer, almost like breathing on glass but probably thinner. Adhesion is superb.

[prb4 6]

Thanks for the extra information.

I've followed the link (thanks) to your website and downloaded the very detailed explanation. I'll give this a go and report back. I use almost exclusively Faberdashery PLA so hopefully this will work well for me.

I also noticed your gentle atomic pull method and have downloaded a copy of that too. I will give this a try next time I do a clean as I have always been concerned about the force exerted during an atomic pull and consequently don't do them until it is absolutely necessary.

One comment I do have is, have you tried going to 240 C during the clean even for PLA?

Your instructions suggest that 210 C is enough to melt the PLA which is of course true but I have always understood that it was a good idea to do an atomic clean from 240 C to melt higher temperature plastic debris (even if I only print with PLA).

Thanks again

Peter

[geert_2 557]

I never go over 210 to maximum 220°C for PLA. This would cause the PLA to get burned, thus worsening the amount of burned material inside. If you have printed with PET or ABS before, and you do the cleaning with PLA, you might try higher temps indeed to melt their residu, but only for a very short time. If you use nylon to do the atomic pulls, you will need a higher temp. It depends on the materials.

The brute force of the traditional atomic pulls is indeed why I developed this more gently method. I did displace the nozzle and teflon coupler a few times, and I worried about bending the rods, or doing other damage. There is no such risk with the gentle method.

[prb4 6]

Hi

I'm reporting back my findings.

I've tried the salt method for sticking to the bed for a few days on a number of different prints.

It did work to a degree but I didn't find it better than the glue stick so I have decided to return to the glue stick.

I am prepared to admit I could be doing something wrong, or perhaps this method doesn't work so well with Faberdashery PLA.

Thanks anyway

Peter

[geert_2 557]

Thanks for the feedback, I appreciate it.

I have never used Faberdashery PLA, so I can not comment on that. But it is entirely possible indeed that some PLA-brands are more sticky than others. If they stick reasonable to an untreated glass (no glue, no salt, nothing), then they are likely to stick better with the salt method too, in my experience. And vice-versa.

Concerning the glue stick: it seems that different brands give different results. For my difficult models, I had poor results with the default glue stick in the beginning: corners did lift, but fragile models got damaged when removing them.

That is why I searched for an alternative method and came up with the salt method, which (for me) did not have both problems.

But that was before I read that you could spread the glue out with a wet tissue, and it may have been a different brand of stick. And it was long before I read about neotko's method of using window-cleaner to remove models.

So I think there is no "best method" that suits for everyone, every filament, and every model. But there are lots of very good and usable methods for different circumstances. So you should try a few and then use the one that suits your models, your environment (moisture, temp, etc.), and your filament best. And important: choose one that you like.

[nzo 16]

Hi Geert,

Your previous help via this forum and your tutorial site were extremely useful. I wanted to let you know what a relief it is to have your saltwater method as a tool. It hasn't let me down yet.

I've moved on to slightly more ambitious prints and that fine salt haze on the glass makes PLA adhesion rock-steady. Thank you again and I hope life is going well for you.

[phut 0]

After learning of the salt method I have been experimenting with it and PETG.

 

PETG adheres well to plain glass (reportedly) and sometimes even breaks it during cooling (reportedly). I had been using the glue method: whilst can be reliable has been a hassle and eventually messy and I wanted to find something cleaner and quicker.

 

Whilst I can't say that the dozen or so prints so far constitute extensive testing, the salt seems to do enough to allow the print to cool uncouple without breaking the glass, but still adhere very well when warm. It's also much more reliable than the glue that with PETG is sensitive to the tack level right before the first layer is laid, as well as usually being an uneven surface that disturbs the first layer.

 

A risk though is that one day a print might be started forgetting that the salt has not been re-laid, and may result in damage to the glass.

[geert_2 557]

Thanks for the feedback.

 

When using dilluted wood glue for PET, indeed I have had chips being taken out of the glass. I already heard weird loud cracking sounds while it was still cooling down, before removing. So I think that was the moment the glass chipped. Mostly I print PET on bare glass, without salt. But in both cases (salt or bare glass) I have to use as little cooling as possible, otherwise large models tend to warp, so for PET bonding is not as good as for PLA. But results may differ a lot from brand to brand.

 

For PLA, since 2 years I always use the salt method with success, although here too there are differences in bonding from brand to brand. The biggest advantage for me is its simplicity. But I still don't really know *why* the salt method works, on a chemical or physical level. I guess it has to do with surface tension: soap and oils reduce surface tension and reduce bonding. Salt on the other hand increases surface tension, and by observation increases bonding (of PLA, not for some other materials), so it might have to do with surface tension too? Or would mechanical grip around the salt crystals, on a microscopic level, also play a role?

 

So if there would be any chemists around here, feel free to add your viewpoint. Educated guessing is also okay for me, as long as you tell so.

 

[smorgana 0]

Wow.  I found this topic trying to figure out how to adhere PLA to the build plate.

 

Up till now... It would not stick at all to the glass if there was nothing on the glass.. and all I had was glue stick..

 

Glue stick works well .. but too well.. even when it all cools to room temp.. you can't get the part off.. I've read people put it in the fridge, etc.. I end up prying it off.

 

people suggest hair spray.. but I'd like to stay away from it.

 

But I tried the salt method and it's amazing.   The part adheres, comes off easy.. the bottom of the part is nice and smooth.. plus salt cost practically nothing.

[Nicolinux 288]

If you can't get the part off, try dripping some water on the outter perimeter of the object. After a short time the water creeps under the object and you can take it off.

[molliske 1]

I have had some issues with a complex model, warping a little at the some points on the build plate on a S5 using PLA.  I have tried adhesion sheets and they have solved the problem in that the print di0s not warp at the build plate, however releasing the print is extremely difficult and has resulted in destroying the print and the adhesion sheet.. Any experience or advise on printing with adhesion sheet would be greatly appreciated.

[Smithy 1,144]

The adhesion sheets are not recommended for PLA and not needed. They are for more complicated materials.

When you use glue stick on a clean glass, make a few stripes and then distribute the glue stick with a wet towel to get a thin even layer, it should work for PLA very well.

[molliske 1]

Thanks Smithy

ive tried Magigoo and glue stick but always the adhesion is bad at point shapes and curls away from the bed as the print progresses. That’s why I tried the adhesion sheet. Am trying liquid Dimafix at the moment - arrived this morning. Raft or skirt would work but would give a lot of post print work so I’m trying to avoid.  After this run I’ll try another make of glue stick but they are probably all very similar. 

[kmanstudios 1,120]

I make my own adhesion glue using Water, alcohol and recycled PVA and paint it on using a soft brush. It can stick very well, but, @Nicolinux is correct a gently mist of water around the edges will allow water to creep underneath and allow for easy removal if needed.

[gr5 2,176]

@molliske - there's more to it than salt versus glue stick versus wood glue versus dimafix versus adhesion sheet.  There's also rounded corners, brim, heat and most importantly squish.  It's kind of a long video at 20 minutes but this explains why the corners lift and how to keep it from ever happening again:

 

[geert_2 557]

For me, the salt method works very well for long, low, and 100% filled models like rulers, that take 1 to 3 hours to print. Thus for my typical models. I use it all the time, and almost never use any other method. It gives excellent bonding for PLA (may not work for any other materials), when the glass is 60°C. But no bonding at all below 25°C, so models come off by themself after cooling down. No need to remove the glass from the printer. I just drop a few drops of salt water on the glass, wipe it, and ready to go. That easy of use is the most attractive for me.

 

However, narrow but tall models like poles and towers, are more likely to come off. So, for tower-like models I would recommend a brim if you want to use the salt method. I guess because the salt has no flexibility to absorb shocks, contrary to most glues? Or use another bonding method instead. No method is perfect, they all have their good and their weak points.

 

Also, the bonding seems to reduce when the printing takes a long time, a whole day or so. In that case too I would recommend using another method. Not sure why that is, since I still don't know the why of this salt method, I can only guess. But I rarely print such big models, thus no issue for me.

 

Also the infill-percentage has a huge influence on bonding: a 15mm cube, 100% filled, sticks so hard you can lift the whole printer. You would have to hammer it off. But if that same cube is printed *unfilled*, with only one 0.4mm thick sidewall, then it tends to come off: it is sort of peeled off from the sides. I found this out when using such dummy cubes as cooling towers next to fine real models. So, for such empty dummies (or empty near the bottom), I design a brim in CAD now: then it stick rock-solid as before. See the pic below.

 

Overhangs exert a lot of warping force, so they are also more difficult to keep down, regardless of what method you use. If you want a hard bonding test, try printing an inverted prism like this. In that way you can compare various methods.

 

My typical models: long and low, ruler-like, 100% filled. The built-in watermark ruler is in mm and cm.

 

Custom brim designed in CAD around the hollow (at its bottom) dummy tower, and around the feet of the custom-supports. Not needed nor desired for the other parts.

 

Inverted prism as warping test: this one might complete, or might come off and produce spaghetti, thus it is not safe to walk away from the printer now. This is a very hard test: very small bonding area, huge overhangs and huge warping forces, and edges curling up so the nozzle hits them very hard. Even within one material (PLA), and one bonding method (salt method here), there can be a lot of variation due to brands, colors, fillers, and even moisture in the air.

 

Another warping test: this one warped, but completed without falling off.

 

 

[Smithy 1,144]

4 hours ago, molliske said:

Am trying liquid Dimafix at the moment

Dimafix is great for material where you have to hotter bed like 80°C or more, but PLA it will not work well because you usually use 60°C for the bed.

 

When you try a glue stick again, use UHU, because not all bands are working.

 

Check out this video, how I apply the glue stick:

 

[molliske 1]

To all who have responded. Thank you so much. Forgive me for being quiet for a few days while I tried out your excellent advice. As usual I was too near my problem and had overlooked the obvious. Some little more squish was, at the end of the day all that was needed. I turned the first layer flow up to 150% and the result immediately improved. Magigoo and glue stick did just as well. Thanks again.