Redwood Plastics is the plastics distributor who runs this website and one of our most common inquiries is “Hi, I’m looking for the plastic for a greenhouse…” what ends up happening is an educational process, often via email, whereas the options are narrowed down to really your only option: twin-wall polycarbonate. The most common misconception people have is that regular acrylic or polycarbonate (the smooth stuff) is a good option: it isn’t. For one, you’ll be paying a lot more, but more importantly, the R-Value (heat insulation value) and weathering resistance will be much poorer. Acrylic has decent UV-resistance but regular unmodified polycarbonate has poor weathering including from the sun. Both options will be much more pricey than the twin-wall, which you should have been using in the first place.
Twin-wall polycarbonate has excellent R-values and resistance to UV-light and weathering. The 4′ x 10′ x 6mm profile is what we be considered “standard”. Many customers do specify 8mm or even 10mm thick polycarbonate and we often wonder why. Yes, the R-value would increase; however, you lose light transmission value. So are you really ahead? Certainly you are NOT ahead when it comes to price as 8-10mm thick polycarbonate is much more expensive. We’ve had members of the “DIY” community have excellent results with 6mm thick twin-wall in Saskatchewan where winters can reach -30 degrees Celsius. For more information on the tradeoffs between different polycarbonate thickness options, click here.
The benefits of twin-wall polycarbonate are excellent and they include:
-Ease of fabrication via common woodworking tools. Diamond/carbide-tipped blades not required.
-Relatively low price
-Full UV-stabilization/resistance to weathering
-High light transmission
-A product that is meant to be for greenhouse applications!
For a personal response to your questions on twin-wall polycarbonate, contact Redwood Plastics today.
We wanted to bring up something amateur plastic project enthusiasts and “Do-It-Yourselfers” often don’t consider until something goes wrong: the weathering of plastic. This was inspired by the a recent visit from a “diy’er” Jason, a hunter. Jason wanted to show us a table he built for processing his game. It was a homemade outdoor table with a white plastic surface likely natural or virgin-white HDPE or UHMW polyethylene. The surface was discolored and had numerous small cracks where Jason (rightfully) was concerned about bacteria growing in the cracks but even more so, he was curious on what caused the plastic to degrade.
The answer for Jason and the culprit with many plastics is UV (ultra violet light or sun) exposure. The chemistry would take to long to explain but suffice to say the sun has damaging effects on plastic. Many plastics become more brittle and crack while others discolor, usually by becoming yellow. If you’ve ever been to an aircraft museum and seen the yellow tinted plastic (polycarbonate) canopies on aircraft? That’s from weathering and UV-exposure. If you look, very closely, at those canopies you’ll see subtle cracks that create a type of haze obscuring vision, as in the picture below.
In most plastic applications for home machinists and project enthusiasts the UV exposure is more of an annoyance than anything. We recently had a sailboat owner frustrated with the discoloration of his polycarbonate hatches he made: the same issue with those aircraft canopies. The most important thing for your project is to figure out of there would be a safety issue caused by a part weathering. In the case of Jason the hunter the cracks on his table might harbor bacteria but since the meats would eventually be cooked (and raw meat has lots of bacteria anyways) this probably isn’t a critical issue. However, in another application – such as the increasingly common homemade roller coasters – the failure of a part, such as a wheel, could be very dangerous.
If you want UV protection there is some good news. Most plastics can be procured in UV-stabilized versions. The problem is these versions are more expensive and sometimes prohibitively more expensive if the material needs to be shipped in on a special order. In the competitive world of plastic distribution there simply isn’t margin or warehouse space to stock the UV-stabilized version of every plastic. The other thing you need to realize is that UV-stabilization in plastics isn’t permanent, it just buys you time – usually no visible degradation over 10 years – but the plastic will eventually lose its UV-stabilizing properties and degrade.
The point of this article is to get you thinking and remember to consider on your next project if weathering is a concern. And for those of you with weathered plastic in your applications? Well now you know why!
For more information, contact Redwood Plastics.
We recently found a video on Youtube, and while we can’t vouch for how well it would work in your application, it looks to be an ingeniously simple solution that would apply to many applications other “Do-it-yourselfers” would have. In the video, the publisher needs to fix a hole in his HDPE jet boat (we’re betting this is a fairly common problem).
The video creator’s solution is to take a knife and shave some HDPE from an area under some molding, where it wouldn’t be noticed, then take a regular soldering iron to melt that plastic into the hole. He then takes a blow torch and brushes the surrounding area, which softens it, and allows him to then take 40 grit sandpaper: blending the patch in with the hole. The benefit of this approach is obvious: the plastic and color will be a match and only simple tools are required. In essence, you are grating plastic akin to a skin graft operation. Also, you don’t need to purchase additional plastic to create the patch.
If this idea interests you, check out the video right here:
Plastic synthetic ice is an increasingly popular “do-it-yourselfer” project for hockey fans. The ice allows year round training regardless of weather conditions. This blog is supported by Redwood Plastics, a plastics distributor, and increasingly we’ve had “synthetic ice” inquiries that actually refer to two different applications. “True” synthetic ice is a skating surface and the application can take a couple forms. Primarily training arenas will have the player suspended by a harness while skating on a single sheet. Because synthetic ice requires about 20-30% more effort to skate on, this improves strength and conditioning. The other format is having a full rink of sheets essentially as a replacement for ice.
There are two types of plastic used for this. One is HDPE polyethylene that has additives to make it optimal for skating, this would be “true” purpose-manufactured synthetic ice. Secondly, white-virgin UHMW polyethylene sheet is used. The UHMW is slicker and stronger than the HDPE but, as you might expect, it’s more expensive to the tune of about 25% more. The issue you need to solve as a “diy’er” taking on this project is how to make your rink. The sheets are just that – flat sheets.
There’s no set hardware for the application, though synthetic ice specialists may be able to offer some help. Otherwise you’re on your own and you essentially need to find a way to put the sheets together, tightly, but without hardware or holes sticking about the surface of the sheet. Usually this means the sheets are placed in a cavity that holds the sheets together and prevents them from moving. For example, a frame made of 2×4 wood bolted into the ground along the perimeter. Do not listen to what you might hear on the internet: adhesives or glues for the sheets will not work!
The second reason people approach us as a distributor for synthetic ice is for a simple platform to shoot pucks off of (or at). In this case, the customer requests UHMW polyethylene or ‘synthetic ice’ but they don’t really need that. It’s “overkill”. Truth is, a cheap plastic sheet – HDPE puckboard – will work just fine in this application, taking a beating and still slick enough to shoot pucks off of (but not skate on). When you’re working on a synthetic ice project you really need to know what you’re looking for!
For more information contact us.
We recently came across the website of a creative fellow, Dave Hendricks, from Allentown, PA who manufactures boomerangs. Wood probably comes first to mind when you think of a boomerang but these are a little more hardcore. Polycarbonate plastic machines better than acrylic (less cracking) and it has tremendous impact resistance making it an excellent choice for a tool like this. Admittedly, this is a little bit of an advanced project where you’ll not only need a router but also knowledge or blueprints of how to make a functioning boomerang but it can be done. Some tips on the routering a boomerang can be found here.
Furthermore, you should know that polycarbonate boomerangs will require intermediate skills to throw well. They require better technique, more spin and more power than their wooden counterparts. While this project might be a little obscure it sounds like a lot of fun for the “do-it-yourselfer” looking for a challenge.
You can find out more about these boomerangs at David Hendrick’s website: http://www.bvdrangs.com
You know what they say about simple ideas – sometimes they’re the best!
We found a video of a DIY project where a CNC machine is used to etch a ball maze into a piece of acetal plastic (of which the name of the homopolymer variety is ‘Delrin’). Apparently the project was for students who designed the game from an initial paper sketch all the way through the CAD program. This project is simple enough for students yet creates a functional and fun piece of work. In short, it seems like genius. Acetal is a great plastic for machining, probably the best thermoplastic in holding tight tolerances.
Acetal has numerous other “Do-It-Yourselfer” applications. Most common is probably aftermarket paintball equipment, which we have blogged about previously here. Acetal replaces small, precise metal parts and often replaces polyamide (nylon) in applications where moisture is a concern.
The video is a little blurry but you will still get the gist of the project and the final design: