Prusa Face Shield disinfection

About the Prusa Face Shield

The 3D-printable face shield is a reaction to the urgent demand for the protective equipment required by doctors and other professionals due to the spread of the Coronavirus (COVID-19). The shield is developed and consulted with the Czech Ministry of Health. All tests were performed by leading Czech laboratories and hospitals to ensure conclusive and reliable results.

PRUSA PRO Face Shield

More details about the PRUSA PRO Face Shield including the assembly manuals can be found here prusa3d.com/covid19 

Before you start cleaning

Before you start cleaning the shield, it is important to protect yourself. Use gloves, a facemask and if possible another face shield. For safety reasons, consider the shield you are about to clean contaminated at every possible surface and take appropriate measures!

In case the shield was contaminated directly by aerosol (e.g. cough) and you have another face shield(s) at your disposal, consider throwing this one into hazardous waste. If this is your only face shield, wash it thoroughly under running water first and make sure you have properly disinfected the sink, otherwise consider it contaminated and alert your colleagues.

Prepare your workplace, where you will clean the shield(s). Disinfect the surface of the desk properly before you start.

Don't clean multiple shields at once, separate them into several batches, avoid cross-contamination!

To ensure the shield is cleaned properly, we recommend disassembling it first:

• remove the elastic band
• remove the lower part, the "chin" - gently pull the part down from the visor
• remove the upper part, the "headband" - carefully straighten the side(s) first, then remove the visor

You can use the How to assemble the PRUSA PRO face shield to learn more.

How to clean the face shield

It is highly recommended to submerge (sink) the shield parts into disinfection solutions, this way you will ensure that the solution reaches 100 % of the surface. You can also use aerosol (spray) but apply the procedure at least twice to reach most of the surface.

Select one of the disinfecting methods from the table below, let the solution do its job. Most of the solutions will evaporate after several minutes. You can remove the remains using a paper towel, avoid using the same towel on multiple shields, avoid cross-contamination. Always wipe in one direction.

Recommended methods

The methods listed below, seem to be the most promising to kill the virus and are currently being verified by the professionals. Hospitals and other medical workplaces can use their professional sterilizing equipment to properly sterilize (disinfect) the face shields before using them again. A test on a single shield is recommended to verify possible damage of the sterilization.

All tests were performed by leading Czech laboratories and hospitals to ensure conclusive and reliable results. Detailed info about the testing facility and conditions of the test are described between the tables.

The tests were conducted on the Prusa Face Shields printed from Prusament PETG Orange. The official design of the Face Shield is available at PrusaPrinters. We cannot guarantee the methods will work on a different design (geometry) or material due to different properties (e.g. PLA will melt if exposed to high temperatures).

*Tested on the WHO Handrub formulation 2

**Higher Ethanol concentration significantly decreases its effectivity

ad 1) SYNLAB - www.synlab.com

Czech based laboratory, a part of the international SYNLAB group. All the tests included:

• applying COVID-19 positive solution on the Prusa Face Shield
• performing the disinfection method
• smear test from the shield's surface
• specimen evaluation for active/inactive organisms

ad 2) UCT (University of Chemistry and Technology Prague) - www.vscht.cz

One of the country's largest educational and research institutions focused on the chemical industry. All the tests included:

• applying Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus solutions on the Prusa Face Shield
• spraying the disinfection solution on the face shield
• waiting for the solution to evaporate
• smear test from the shield's surface
• specimen evaluation for active/inactive organisms
• test protocol in the Czech language is available here

ad 3) LABTECH - www.labtech.eu

Accredited laboratory with almost 30 years of experience, also a producer of the testing equipment. All the tests included:

• applying the Coagulase-positive staphylococci solution on the visor of the shield
• spraying the disinfection solution on the face shield (2x applications)
• waiting for the solution to evaporate
• smear test from the shield's surface
• specimen evaluation for active/inactive organisms
• test protocol in the Czech language is available here

ad 4) NIPH (National Institute of Public Health) - www.szu.cz

A national organization funded by the Ministry of Health, responsible for disease prevention and monitoring. All the tests included:

• sterilizing the shield in the steam sterilizer

ad 5) Health institute Usti nad Labem - www.zuusti.cz

A public health organization coordinating its activities with the Ministry of Health, part of the system responsible for protecting public health. All the tests included:

• applying solution with bacteria on the Prusa Face Shield
• performing the disinfection method
• smear test from the shield's surface
• specimen evaluation for active/inactive organisms

Soap and hot water

The tests in the labs brought fairly good results for the combination of soap and warm water, but the ingredients in the soap may vary across the world. It is, however, highly advised to use the "recommended methods" instead (see the first table), as those methods have been properly verified. However, if no other disinfectant solution is around:

• pre-wash the parts of the sheet using a hot water
• apply the soap and warm water, make sure you've reached all surfaces
• wash all the parts carefully for at least 2 minutes
• apply fresh warm water and remove all the soap
• (optional) repeat the entire process once again
• let the parts dry

Not recommended methods

The methods listed below were tested and evaluated as not ideal for the disinfection process or causing structural damage to the shield.

"Czech" disinfection solutions 

This section is dedicated to disinfection solutions, which can be bought in the Czech stores or pharmacies. A similar product might be available at your local store. Each product has a link to the producer or reseller. The tests were performed in the Prachatice hospital (Czechia).

The tests included:

• collecting the shields at end of the shift at the hospital
• applying the disinfection solution
• waiting for the solution to evaporate (dry out)
• smear test from the shield's surface
• specimen evaluation for active/inactive organisms

Note: these products might leave stains, use a wet towel afterward to clean the visor