/diy/ - Do It Yourself

>>2736199
Visual inspection is not nearly good enough for hospitals or food establishments. So, we must use other testing methods to determine how clean they are. Protein Residue tests directly measure organic/microbial contamination.

The same procedure was then repeated but using the protein residue swabs to test the 3D printed mask that I had inoculated with Salmonella typhimurium 2 hours previously. You can see the control swab and how it has turned purple, this indicates an abundance of proteins. I then washed samples of 3D printed parts with Salmonella in just warm water so that I could take a protein swab test for a control. The test turned purple since water was not able to wash all residues away.

Let us compare results after washing a second piece of the mask with basic soap and water as well as some cubes and first layer prints that have been inoculated with Salmonella typhimurium as well. No alcohol was used for the second set. We want to see how well basic soap and water can clean items since during times of pandemics, rubbing alcohol (IPA) or even bleach can be very difficult to come by.

The printed parts were tested at 2 hours and 24 hours after cleaning. The control is shown against the green solution. Green is clean. No proteins after 2 and 24 hours after cleaning with basic soap and water. This means nothing was left behind to allow pathogens to grow and multiply. If they were to grow, they would leave behind new contamination which the protein swabs would pick up.

I confirmed my findings with another tester, who did a wash in soapy water, rinsed the part, then sanitized it by soaking it for 5 minutes in bleach water at the hospital. The 5-minute time frame was to allow the bleach water to seep into the part. The surgical technician then did an ATP and protein swab test. They found the parts to be well within spec and useable for a medical setting.