Material Spec Checklist: Covestro Polycarbonate, Medical PTFE, ABS, and Foam Board

If you're ordering custom plastic parts, printed panels, or medical-grade components, this checklist is for you. It's six steps. I've been handling material orders for about eight years, and in that time I've personally made and documented 23 significant mistakes—roughly $37,000 in wasted budget. Honestly, most of these mistakes were avoidable. So now I run this list before every PO, and it has caught 47 potential order errors in the past 18 months.

Before you read further, this is not a complete engineering guide. If you're designing an implanted medical device or a load-bearing aerospace part, go read ISO 10993, talk to a regulatory consultant, and don't rely on a blog checklist. This list is for the other 90% of orders—prototypes, enclosures, signage, mounting boards, and short production runs.

Who should use this list

Use it when someone says 'we just need a plastic part,' or 'make it out of polycarbonate,' or 'we want foam board.' Those phrases are not specifications. This checklist turns vague requests into concrete requirements before you spend money.

Step 1: Write down the exact polymer family and grade

Do not order by acronym alone. I learned that in 2017, when I ordered 'ABS' for a customer and got a sheet that looked fine but had terrible impact resistance at low temperatures. The lesson: ABS stands for Acrylonitrile Butadiene Styrene. I know that sounds like the answer to a trivia question now, but the chemistry actually matters. Acrylonitrile gives stiffness and chemical resistance, butadiene gives impact strength, styrene gives processability. Different grades balance those three differently.

The same applies to polycarbonate. If you search for 'polycarbonate Covestro,' you'll get a long list of grades. The right one depends on whether you need UV stabilization, flame retardance, food contact, or hydrolysis resistance. For example, standard polycarbonate can crack in contact with some chemicals, and it can degrade if it's repeatedly steam sterilized. Covestro's hydrolysis-resistant polycarbonate grades exist for a reason. But 'polycarbonate' alone is not enough.

Checkpoint: Write the full trade name, grade, and manufacturer. If you can't find a data sheet, stop.

Step 2: Define the environment before you choose a material

A part that works in dry indoor air might fail in a humid room. We didn't have a formal spec review process for this. It cost us when a 500-piece order of polycarbonate enclosures looked perfect out of the box, then turned cloudy after the first heat sterilization cycle. That's a mild way to say we threw away about $2,800.

When I compared our Q1 and Q2 orders side by side, same vendor, different specifications, I finally understood why the details matter so much. The parts weren't wrong. The environment was never specified.

Checkpoint: Write down temperature range, humidity, UV exposure, chemical contact, and sterilization method. If you can't answer all five, go ask the end user.

Step 3: Get the data sheet and traceability before you buy

For any plastic, ask for:

• The technical data sheet (TDS) for the exact grade.
• The safety data sheet (SDS), if you're shipping by air.
• Lot traceability, especially for medical PTFE.
• A statement of compliance to the relevant standard, not a vague 'we think it meets.'

This step is the one people skip. They assume the supplier will send the right material if they order from a big brand. That is not how it works. In September 2022, I ordered 'medical PTFE' and got a certificate from the resin manufacturer, but not from the fabricator who converted the resin into the tubing. The lot numbers didn't match. We caught it before surgery, not after, but the delay cost us the schedule.

Also, if you're planning to market a product as 'recyclable' or 'recycled content,' verify the claim. Per FTC guidelines (ftc.gov), environmental claims need to be substantiated. That is a legal requirement, not a marketing preference.

Checkpoint: Does your supplier's documentation refer to the exact product and lot you're ordering? If not, ask for a corrected certificate before payment.

Step 4: Check dimensions and tolerances against the real application

This is especially important with foam board. Foam board dimensions are not universal. A 24×36 board from one supplier might be slightly thicker than the same size from another. The thickness can be 3/16 inch, 1/2 inch, or something in between. If you're mounting a 24×36 print, the board may need actual dimensions of 24×36 or a little larger, depending on the supplier. Do not assume.

For printed panels, resolution matters too. Industry practice is 300 DPI at final size for close viewing, and 150 DPI is acceptable for large-format signs viewed from a distance. On a 24×36 inch board at 150 DPI, you need at least 3600×5400 pixels. A 3000×2000 image will look soft. I found this out after paying for rush printing of a customer's 24×36 display. It looked bad from arm's length. We reprinted it—again, rush—and it cost double.

Checkpoint: Write down finished part dimensions, material thickness, print resolution, and the tolerance for both. If the drawing says 24×36, confirm whether that's the board size or the image size.

Step 5: Ask specifically about medical PTFE

'Medical grade' is one of the most overused phrases I hear. For PTFE, the actual requirement is usually biocompatibility testing per ISO 10993, and often a specific cleaning or sterilization validation. The supplier should tell you which tests were run and which standards were used. If they can't, it's not medical grade; it's just a part that could end up in a medical product.

Another tip: don't assume the material comes from the same brand you use for polycarbonate. PTFE suppliers are usually specialists, and that's fine. What matters is the documentation. I should add that we now have a folder for every material certificate. It's boring, but it saved us when an auditor asked for traceability. The 'medical grade' quote you get from a certified converter may cost more than the generic one. That's normal. What matters is whether the extra cost buys you enough documentation for your application.

Checkpoint: Can the supplier provide the ISO 10993 test report and a statement of lot traceability? If no, keep looking. If yes, make sure the report is for the exact grade you're ordering.

Step 6: Do a small test order before production

I know this sounds like extra work. But the first order after this checklist saved us. We ordered a small piece of Covestro polycarbonate with the specs we had written down, tested it with the actual cleaner we use in production, and it cracked. We got lucky—it was a $190 test piece, not a $19,000 production run. The previous version of us would have skipped this step and paid much more.

Test orders are not necessary every time. If you've ordered the same grade from the same supplier five times with no issue, you can reduce the frequency. But for anything new, new material, new supplier, new tolerance, new environment, start small.

Checkpoint: Have you tested the exact material, surface finish, and color in the actual environment? If not, schedule a test order.

Common mistakes after you think you have it right

Three things still catch people.

1. They swap 'equivalent' materials without checking the data sheet. ABS from one supplier is not necessarily the same as ABS from another. What does ABS stand for plastic? Acrylonitrile Butadiene Styrene. But the ratio changes performance.
2. They trust the browser preview for foam board prints. The color on your screen is basically meaningless. Ask for a physical proof if color matters.
3. They ignore the fine print on lead times. We got a quote for 'standard lead time' but it did not include the raw material wait. The actual delivery was almost two weeks later—or rather, closer to three after they needed to redo the surface finish. So ask, 'What is the lead time from approved drawing, and what happens if the material is out of stock?'

Bottom line: no plastic is the best across the board. Covestro polycarbonate is a good choice for many impact-resistant and clear applications, but it is not right for every job. PTFE is great when you need low friction and chemical resistance, but only if you verify the medical documentation. ABS is a solid, machinable workhorse, but it has limits. Foam board is easy to get wrong because the dimensions and specifications are too often assumed. Run this checklist before your next order, and you'll probably save yourself a few weeks and a few thousand dollars.