There are a lot of outdoor enthusiasts who are interested in food-grade plastic cutting boards. But it for an outdoor kitchen to something exotic like a fish cleaning station on a boat. The applications might seem different; however, the same family of plastic, polyethylene, is almost always used. But which plastic to use? What concerns are there?

Both UHMW (ultra high molecular weight) polyethylene and HDPE (high density polyethylene) in their “white” or more correctly, “natural” grades are FDA and CFIA approved for direct contact with food. HDPE, even though it’s less expensive, is preferable because unlike UHMW, it will not dull knives over time. If you have UHMW lying around it’s certainly a good option though and is probably worth the trade-off vs. buying a whole new sheet of HDPE. UHMW is commonly available in 4′ x 10′ sheets but many plastic companies will send you a partial piece of that sheet (with a nominal cutting fee included). HDPE is commonly available in 4′ x 8′ sheets though many companies also stock it in 4′ x 10’s.

Cutting the plastic to size is easy: household power tools such as drills and saws will easily cut it. Having a 40 grit sandpaper on hand would be good to deburr the cut edges. The plastics glue very poorly so if you’re installing a blacksplash, for example, attached to the cleaning station or cutting board you will need to screw it in. 3/16″ or 1/4″ self-tapping screws 6-12″ apart should be fine. The plastics are soft enough that your drill will countersink the heads slightly.

The problem with these natural grade plastics is that they are not UV-stable. You should expect some cracking of your cleaning station if exposed to the sun in about two years depending on exposure. The board surface should be seen as a “sacrificial” surface which will need replacement every few years – just part of the gig. The surface will become brittle and crack which isn’t good because it allows bacteria to hide in the crevices but otherwise this degradation does NOT make the plastic toxic.

If you need assistance or a quote on either of these food-safe plastics, please contact Redwood Plastics and Rubber.

 

SDS Documents

Posted: March 21, 2019 in Uncategorized

Commonly requested from plastic companies by industry and government are “SDS” or ‘Safety Data Sheets’ (sometimes also referred to as MSDS). These sheets give a range of information on potential hazards of plastics and are legally mandated for plastic producers to produce and regularly update. Where these sheets intersect with the DIY community is that home machinists and fabricators should be aware of any hazards with the materials they’re working with too. The sheets will cover what to do if the plastic shavings or dust touch you or enter your eyes or lungs, for example. The good news is in most cases these plastics are simply irritants and won’t cause harms but others, such as phenolic industrial laminates, can cause more issues.

Due to changes in U.S. Federal law plastics distributors can no longer rebrand and pass off SDS data as their own. Instead, distributors such as Redwood Plastics and Rubber need to supply SDS documents straight from the manufacturer. So this means the documents are somewhat harder to come by these days. However, for the home fabricator the most recent SDS isn’t required and Redwood still keeps some old SDS documents on their site. You can access them here: https://www.redwoodplastics.com/tools-data/msds/

Plastics are very recyclable in general and it is a travesty that poor recycling behaviors have given the material an undeserved bad reputation. Efforts begin at home and fortunately LDPE and HDPE, two common household plastics, can be melted down using household appliances and then remade into new objects. The video we are sharing below doesn’t actually teach you what to make with the polyethylene recycled plastic; however, it does teach you a simple way to melt the plastic into a brick, which could then me fabricated into a new project or alternatively, melted down into a new mold.

In less than five minutes this video will provide you with the essentials to recycle your own HDPE and LDPE:

Breaking Down “Phenolic”

Posted: February 13, 2019 in Uncategorized
Tags: , ,

Phenolic laminates (properly termed “industrial laminates”) are one of the largest groups of plastics, a large family that consists of five primary resin binders (the actual ‘plastic’) plus a substrate (glass, cotton, or paper material) to form a composite “sandwich” that is tough with strong mechanical properties. As such, you really need to know what industrial laminate you actually need for your project. Step one is not making assumptions: if you’re unclear, ask a knowledgeable plastics representative who will work with you by asking pertinent questions that will help select the best laminate for you.

In most cases where mechanical properties are desired, simple C/CE grade laminate will suffice. This is a brown colored material that is commonly stocked by distributors and uses a cotton substrate. These laminates are made from true phenolic resin. For electrical applications, FR-4 is used. FR-4 is also commonly stocked but comes at a higher price point than the C grade laminates. These two laminates will makes up perhaps 95% of the applications for the DIY community. Melamine-based laminates are often inexpensive and brought in from Asia, these are used as cupboards or table tops for residential construction. Silicon and polyester laminates are used much less often in DIY applications.

The main property you can expect from industrial laminates is excellent mechanical strength and rigidity. Many thermoplastics are pliable to some degree but laminates are very hard. This makes them serve well as spacers, load pads, and bearers of static load. They do have a high coefficient of friction and are not good at dynamic wear.

One of the most common questions the DIY community has is trying to figure out what type of plastic they have or need. Maybe you have an old part or sample and you forget what it is? Perhaps the two plastics people most want to differentiate between are acetal and UHMW (or other polyethylene). But they both come in white and black and they kind of look similar, so what to do? Well, if you’re familiar with the two plastics UHMW or HDPE will feel different: more waxy and lighter than the acetal which almost feels like more of a metal than anything.

There’s another way to identify polyethylene though as long as you can disfigure the sample. Take a sharp knife, such as a steak knife, and start scraping the plastic, give it some gusto with long strokes. If the plastic shaves off in curls then you have polyethylene. Acetal and other plastics will not do this, an example of polyethylene with this type of shaving is pictured here:

 

Part of the trick of figuring out your plastic application and finding which type of plastic to use. This is because 1.) engineering plastics are not widely known to most people and 2.) several of the plastics may work in an application. The trick is to find out which plastic is ideal in a given application, but how do you do that? Well, first you need to figure out what your priorities are either regarding properties: do you need a plastic with excellent impact-resistance? Or perhaps slickness? How about the ability to hold tight tolerances when machined?

After you pick your top couple priorities the next step is find a plastic that best matches your needs. Redwood Plastics and Rubber offers a handy webpage with some information here. However, we’ll also copy and paste the contents of that page below:

SLICKNESS (Most to Least)

Redco PTFE (Teflon®)

Redco UHMW

Redco Tuffkast

Redco Polyurethane (Redco 750SXL)

Redco Nylon

Redco Polyurethane (Redco 750)

Redco Phenolic

 

 

MAXIMUM TEMPERATURE (500+ F) (260+ C)

Redco PTFE (Teflon®) (500 – 600°F)

Redco Phenolic (400 – 500°F)

Redco Nylon (240 – 275°F)

Redco Tuffkast (220 – 240°F)

Redco Polyurethane (200 – 240°F)

Redco UHMW (160 – 180°F)

 

 

HARDNESS

Redco Phenolic

Redco Nylon

Redco Tuffkast

Redco Polyurethane (Redco 750 & Redco 750SXL)

 

 

GLAZING

Breakage Resistant Windows

(Redco Acrylic/ Redco Polycarbonate)

Security Windows

(Redco Acrylic / Redco Polycarbonate)

 

 

LOAD STRENGTH (P.S.I)

Redco Phenolic (10000)

Redco Nylon (4000)

Redco Tuffkast (3800)

Redco Polyurethane (3000)

Redco UHMW (500 – 800)

 

 

IMPACT STRENGTH

Redco Polyurethane

Redco Tuffkast

Redco Phenolic

Redco UHMW

Redco Nylon

 

 

SHOCK & VIBRATION

Redco SVI PADS

 

 

(KRAFT MILL) PULP SAFE

Redco Synsteel (Redco UHMW)

Redco SPS-2000 (Redco POLYURETHANE)

 

 

LOW WATER ABSORPTION

Redco Acetal

Redco UHMW

 

 

BRAXX Anti-Slip Sheeting

Posted: December 20, 2018 in Uncategorized
Tags: , , ,

Ever worked on a home project where you need a rugged anti-slip surface? Could be stair treads, maybe the side of a pool, a deck or anywhere slippery. One option is BRAXX anti-slip sheeting for an application that does not require load bearing material, IE. you are going to simply screw, nail, or bolt the anti-slip surface into a substrate. BRAXX comes in a standard 3′ x 9′ sheet that is 0.30″ thick and this is the only size available. There are two options, a blue UHMW plastic with sand surface anti-slip buttons or the more popular safety yellow UHMW with LUNS (clean coal slag) anti-slip buttons. See picture below for detail of each. This product is very strong as UHMW cannot break and it was originally developed for military applications such as the floor surface of naval tank carriers.

The product cannot be ‘glued’ using a liquid adhesive. Mechanical fixation is required but there is no special hardware for this…Nails, bolts, screws, whatever you have lying around will work. UHMW is easily fabricated with power tools found at home. This is a premium product, you can expect a cost of approximately $600.00/sheet US funds before freight is factored in. However, for a premium anti-slip surface from the demanding DIY individual, it’s the best there is.

This product is available from Redwood Plastics and Rubber: http://www.redwoodplastics.com