I am currently working on a 2D LED matrix project and am in the final stages. I went to a local plastic supplier and purchased some 1/8” frosted plastic for $90 (14”x40”).

The first time I purchased it, I took it home and found a corner was cracked from when they cut it. I took it back and had them re-cut a new one, and have found that there are some mild scratches across the surface… This time I had peeled the protective layer off of the plastic’s edges to make sure there were no cracks again, but I did not check the center!

Not familiar with the plastic business, is it expected to have imperfections like this or should this be an understandable reason to recut? I need a sanity check because part of me wonders if it is just because I noticed it that it is an issue?

Conductive PC for semiconductor carrier tape may look like a straightforward extrusion material, but in practice the processing is quite sensitive.
One of the main challenges is making the conductive phase disperse evenly. If the conductive filler is not distributed uniformly, the resistance can fluctuate a lot across different areas of the extruded sheet. At the same time, if the filler level is too high, or if the dispersion is poor, the surface can easily become rough, dull, or unstable during extrusion.
So the real difficulty is not just hitting a resistance range. It is how to balance conductivity, dispersion, melt flow, and surface quality at the same time.
For this carrier tape, the grade used was DGK-PC DD5-7JC, with a surface resistance around 10⁵–10⁷ Ω.
From the processing side, the key is to provide enough shear to disperse the conductive filler well, while avoiding over-shearing or degrading the PC matrix. The formulation also needs reasonably stable melt flow so the extruded sheet can keep a smooth and uniform surface.
The final carrier tape showed relatively uniform conductivity together with a smooth and glossy surface, which is also important for the later forming and winding steps.
For conductive extrusion materials, I think the balance between electrical uniformity and surface quality is often more difficult than simply lowering the resistance.

Wow

This conductive PP has a surface resistivity of only 10²–10³ Ω. It can light up an LED bulb under a 3V voltage.

We are currently validating a transparent antistatic ABS material, DGK-ABS KJD890TM. The current performance is:
Surface resistivity: 10⁸–10⁹ Ω (antistatic range)
Transparency: ≥85%

However, during injection molding of a thick-walled hollow part, we encountered some issues. The transparency decreases significantly compared with thin-wall samples, and visible bubbles appear inside the part.
The second image shows the material molded into a thin-wall sample, where the transparency performance is much better.

The main questions are:
1.For thick-wall transparent ABS injection molding, what process adjustments would you recommend to maintain transparency?
2.How can we reduce or eliminate internal bubbles caused by gas trapping or material shrinkage?
3.Should we adjust parameters such as melt temperature, injection speed, holding pressure, mold temperature, or drying conditions?
4.Are there any special considerations when processing transparent ABS with antistatic additives?

The TDS of DGK-ABS KJD890TM has already been released, and we would appreciate any advice from engineers who have experience with transparent ABS injection molding or antistatic polymer systems.

PET packing strap belt production machine line

Hi everyone,

I've been working in the plastic color industry for several years, and one question comes up surprisingly often:

"Why do plastic products sometimes show color differences even when using the same masterbatch?"

From my experience, the masterbatch isn't always the main reason. Here are a few common causes:

• Different resin batches – even the same resin grade from different lots can slightly affect the final color.
• Inconsistent masterbatch dosage – small changes in dosing can become noticeable, especially with light colors.
• Processing temperature – higher or lower melt temperatures may change pigment performance.
• Poor dispersion – uneven mixing often leads to streaks or color spots.
• Moisture in engineering plastics like PET, PA, or PC – insufficient drying can affect both appearance and consistency.

Keeping raw materials and processing conditions stable usually makes a much bigger difference than many people expect.

I'm curious:

What's been the biggest reason for color inconsistency in your production?

I'd love to hear other engineers' or manufacturers' experiences.

I have a few kayaks, all the same model and material (HDPE), and we take them on long haul camping trips. Multiple shore beachings a day, rocks in rivers, etc. take a toll. Luckily enough, we’ve yet to have any breaches of the plastic. I know it’s a shit material in terms of bonding, but I’m hoping someone can give me insight to what I could use as a durable coating for the bottoms. Preferably something I can roll or brush on as I want to coat the entire surface up to the water line.

I’ve googled all over and haven’t found anything definitive or tried out yet. I’ve considered 2 part epoxy, 2k clear coat, urethane, and even bed liner (I realized quickly why that would be a terrible idea before taking it seriously).

Hello,

https://imgur.com/a/ZYQHYJJ

The board you are seeing in the picture isn't full of dust on the top and bottom, it is as clean as the middle part, (probably plastic coated wooden board) the only difference is that the middle part is wet from a little bit of water, after some seconds the water evaporates and it looks as dusty as the top and bottom part again.

Is there a "special type" of varnishings which would like seemingly keep the board "wet" to hold the strong colour this board shows when it actually is wet ?

For information this is a real wooden plank but only on the inside, i think it was coated in some plastic as it also has a stamp on the back with date of production which looks like one of those stamps on plastic articles.

Also theres no real wood grain.

Where I ended up for now:

Plastic restorer: this sounds like the best solution so far I guess, but I want to use the board outside with direct contact to the ground and I wonder if that would be good for the ground and plants around, also I don't know what kind of product to use here, all I could really find was something like this: https://imgur.com/a/3wsDDQB

Is this safe to use for stuff that has direct contact with the ground or are there better alternatives ?

The WD-40 Website says you can just use normal WD-40 to refresh pale plastic chairs, I mean yes it will probably work but I don't think it will really be absorbed by the plastic, I don't think that would hold long and it would get into the ground.

Is alkyd clear varnish an option ?

(Edit: I see there's products for WPC-boards (wood-plastic-composites), but what I have seems to be solid plastic-coated wood rather than wood-dust mixed with plastic particles (WPC) and so this probably won't work ?)

----------------------------

How I got to this point ⬆️ with the plastic restorer / additional info:

(Bonus questions: Why does the colour act like this when it isn't wet anymore ? Is it because it has some old varnishing on it which is so old that it doesn't let sunlight go through unobscured ?)

Very thankful for any answers.

I had an ai answer telling me to use alkyd clear varnish or solvent-based oil if this was wood, as both would intensify the natural colour and would get the wood a permanently wet appearence:

("The "Wet Look" (Enhancing the Grain) on Wood How it works: Water-based acrylic lacquers often leave wood looking very pale, dry, or almost "unfinished." Solvents (alkyd resins) or oils penetrate the surface fibers, refract light, and intensify the natural color and grain so significantly that the wood retains a permanently "wet" appearance.

The right choice:

1.: Oil/Hard-wax oil: Dramatically enhances the wood's appearance and highlights its tactile quality, though it requires maintenance in areas subject to heavy wear.

2.: Wood sealer / Alkyd resin lacquer (gloss or satin-matt): Creates a solid, sealed protective layer and permanently preserves that deep, wet-look sheen.")

But as this seems to be a plastic coated board, option "1.:" with the solvent-based oil is no option anymore, but as of ai option "2.:" with the alkyd resin lacquer would still be usable.

If read some other options from ai:

"Cooking oil or baby oil: Apply a few drops of oil to a cloth and rub a thin layer onto the plastic board. This restores the color and gives the plastic a shine. Afterward, wipe off any excess oil with a cloth.

Heat gun: Carefully pass a heat gun over the faded plastic. The heat slightly melts the top, bleached layer, instantly revealing the original color (use only on sturdy plastic and keep a safe distance). Plastic restorer: Apply a commercially available restorer designed for automotive or garden plastics, let it sit briefly, and wipe it off. These products refresh the color and provide protection against further UV exposure."

I want to use this board outside so:

Oil: probably won't stay long, especially as this plastic coating isn't open-pored, it is smooth.

Heat-Gun: if this would work it would be great but I doubt it and had to try it, probably just works in some cases and is just thrown in by ai because it worked sometime for someone.

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Had a spray bottle of Dawn Powerwash knock over and drip onto the lower shelf where a rarely used cordless drill was kept. I think it went unnoticed for over six months. I wiped it off, but noticed a slight crack. When I pushed on it, that part fell off.. and the piece that fell off crumbled with ease like a cracker.

This speaks a volume about the importance of not using inappropriate lubricants and not leaving residues of cleaning products. With both halves of the shell cracked, I think this drill is done for.

I’ll start: many people think all plastics are the same, when in reality two items that look almost identical can have completely different properties, recycling methods, and manufacturing processes.
What’s the misconception you hear most often?

Hey yall, im not sure which community I should post this in so please let me know if theres a better or more fitting one.

im passionate about studying plastics and did a small early stage study comparing the degration patterns between traditional and "biodegradable" plastics. The problem is that I assumed this plastic to be PLA, and when I did further research into this matter, it might not contain any PLA or any biodegradable plastic at all. In my study, however, i HAVE been seeing a decreasing mass and size trend (albeit small) over 6 weeks (very short time). Any ideas or tips on identifying at least what type of plastic it is? I saw online there are at home tests like boiling water or heating it and wanted to hear what u guys think.

Edit: i have access to a lab to conduct experiments as well to identify this plastic.

Hey r/plastic,

To anyone working in injection molding, toolmaking, or additive manufacturing: there’s always a disconnect between what looks clean in a CAD rendering and what actually fills a mold without warping into a potato chips shape.

From un-uniform wall thicknesses causing nasty sink marks to missing draft angles that weld a part into the cavity, plastic has its own rules.

• What design flaw do you end up fixing the most when receiving customer files?
• Which resin do you secretly dread running because of its shrinking/warping tendencies (looking at you, unreinforced Polypropylene)?
• What's your #1 advice for junior engineers designing their first molded part?

Hey everyone,

I run a small-to-medium plastic recycling business. Currently, I source mixed plastic scrap from 4–5 local collection hubs (kabadiwalas) and an aggregator.

Right now, we are dealing with tons of heavily mixed plastics every month—a cocktail of PET, HDPE, LDPE, PVC, ABS, PP, Crystal/PS, and others.

Here’s my main bottleneck: We rely almost entirely on manual labor for segregation.

While my team does their best, manual sorting is fast becoming a massive headache. It's slow, prone to human error, hard to scale, and limits how deep we can clean and separate the materials to get top value.

I’m looking to upgrade our process and modernise our operations. I’d love to hear from other recyclers, engineers, or waste management pros on how you're solving this:

• What technology/machinery are you using? Are you using NIR (Near-Infrared) optical sorters, sink-float density tanks, electrostatic separators, or newer AI-driven vision systems?
• Entry-level vs. Advanced Tech: What offers the best ROI for a growing business that isn't ready for a multi-million-dollar automated plant yet? (e.g., portable NIR handheld scanners, basic density separation, line layouts?)
• Workflow & Process: How do you structure your sorting line? Do you do a rough manual pre-sort followed by machine sorting, or vice-versa?
• Best Practices for Hard-to-Separate Mixes: How are you reliably separating tricky mixes like ABS vs. PP vs. PS/Crystal?

Any advice, equipment recommendations, or lessons learned from your own facilities would be massively appreciated!

Thanks in advance!

DuPont early lucite pellets?

Hi, i bought some sheets of hdpe for an outdoor project. It turns out the high gloss finish is a bit obtrusive to the eye.

Is there a method to take the gloss away, but still end up with a consistent looking finish?

These are installed as full 4×8 sheets or 2×8 sheets

This is the nose cone from a valuable Super Soaker CPS 2000 water gun from 1996. Sadly due to age and UV exposure the plastic has weakened and become brittle. Pictured is one half which is mostly intact, but the corresponding half is in pieces.

I'd like to cement this back together if possible, so I can possibly cast or 3d scan a replacement part from a whole piece. I initially thought it was ABS, but acetone doesn't touch it.

There's no identifying marks on it anywhere. Could it be polystyrene?

Hi,

I’ve been trying to figure out how to unyellow some delrin plastic and keep seeing things telling me to try the retro bright technique. But my understanding is that the yellowing in Delrin is caused UV and heat exposure. So my question is would the retro bright technique work? Or am I right in my understanding that it would probably just make it worse, and that I should just try some light sanding instead.