Is Ethyl Alchohol 70% OK for cleaning? Or it has to be Isopropyl Alchohol?  

RE: Is Ethyl Alchohol 70% OK for cleaning? Or it has to be Isopropyl Alchohol?

Just my personal opinion... First we need to define "cleaning". If that's removing dust (or other non-sticking stuff) form printer, then 70% alcohol is just fine -in that sense, it's also good enough to wipe print sheet. But, it must be pure alcohol, without any add-ons! If there's anything like "skin friendly" (or similar) on the label, then don't use it for printer!!
Anyway, alcohol doesn't remove fat (oil, fingerprint, etc), no matter what percentage -you need to use soap for that.

In my country it's difficult to get high percentage alcohol in drugstore (or pharmacy) -or they sell it at extremely high prices.  However, I could find it in workshop stores (where they also have paint colors and thinners) for very cheap. Maybe you should check your local stores.

RE: Is Ethyl Alchohol 70% OK for cleaning? Or it has to be Isopropyl Alchohol?

Thank you, BogdanH. Consider me enlightened.

The Riddle of Adhesion

Here are some notes I've put together based on these discussions over the years.

The riddle of adhesion

You’ve probably seen some of these guidelines before and may have wondered exactly why these simple-sounding steps work. Here’s an unscientific breakdown.

1. Isopropyl alcohol 3 and acetone 4 work as solvents 1 breaking apart grease molecules. These solvents do not completely dissolve grease, but do break it down far enough that it can be removed from surfaces easily.

2. The more concentrated the solvent, the more effective it will be at a given volume. Those little 70% isopropyl wipes do work… on a shiny new PEI sheet. They’re just not effective in dealing with larger amounts of accumulated grease. This is why 91%+ alcohol is recommended.

3. Acetone is even more effective, breaking up oxidation on the PEI surface, but can make the PEI surface brittle and prone to cracking if over-used.

4. The amount of grease that any solvent will effectively break down is directly proportional to the volume of solvent to grease. The more you apply, the more grease it can effectively break down. The more concentrated the solvent, the more grease a given quantity can break down.

5. Alcohol, acetone, and any other solution you apply directly to the bed is just going to move those broken-down grease and grime molecules around. Some will be picked up by wiping with a clean towel, but some will remain on the PEI sheet.

6. A dunk under the sink with Dawn dish soap (or your local equivalent) is the most effective method of cleaning. Dish soap is a surfactant 2 , not a solvent. It works in a fundamentally different way, bonding both grease and water molecules to wash away contaminants. The reason this is so effective is not because Dawn is “stronger”, but because there’s simply a much greater volume of Dawn and water and the grease is washed away from the PEI sheet. Hot water helps break up grease as well, enhancing the effect. Use water as hot as you can safely get it.

7. Windex, a wipe of finger grease, talcum powder or specialized release agents can be used to reduce adhesion when using hot, sticky materials that grip the PEI surface too firmly such as PETG. It is still a good idea to clean the PEI before a print to get an even surface, even if you will be applying a release agent for printing with sticky materials.

8. If you are printing high-temperature materials (e.g. PETG at 260C on a 90C bed), test to make sure it will release once cool without damaging the PEI surface. You may want to use a glue stick or other release agents for these materials. Test on a sacrificial PEI surface if possible. See over adhesion, below.

RE: Is Ethyl Alchohol 70% OK for cleaning? Or it has to be Isopropyl Alchohol?

Thank you, Bob.

Incidentally, I am reading your blog on Muppets Lab with great interest.

RE: Is Ethyl Alchohol 70% OK for cleaning? Or it has to be Isopropyl Alchohol?

Ethanol, like all alcohols, is a solvent.  It has soap like properties, but unlike soap, you don't get the wash it away with water part - as  noted above.  You might find higher % if it is denatured (USA speak), methylated (Brit speak), or similarly made undrinkable and so untaxed at a dirt cheap price.

I stock 99% IPA, and use it often, but only because I am lazy.  The best results by far are soap and water.  Unless you are factory printing all day long, just run your plate to the sink for a good soap and water scrub for a happy printing life.  It only takes a minute, and soap and water is really affordable.