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UV Light Curing: Why Use a Radiometer?

March 27th, 2013
 

Radiometer

A radiometer is an important tool in the light-curing process. Below are a few of the benefits of using a radiometer to monitor your light-curing process.

Benefit 1: Maintain a Reliable Light-Curing Process

UV-curing bulbs, lightguides, and reflectors can deteriorate over time, causing less UV energy to reach the cure surface and result in incomplete cures. As the UV energy decreases, adjustments in the process must be made to maintain product quality. It can be difficult to determine when the UV energy is decreasing. UV wavelengths of light are too short to seen visually with just one’s eyes, requiring the use of a radiometer to monitor intensity. Radiometers measure the intensity and/or energy associated with light of specified wavelengths. A radiometer can measure whether a light-curing system is providing intensity above the minimum or “bulb change” intensity. A radiometer is to a light-curing process what a thermometer is to an oven-curing process.

Benefit 2: Provide a Safer Work Environment

A radiometer can also be used to determine if any stray UV light is reaching operators or bystanders. This can help insure a safer, more worker-friendly light-curing process. Dymax’s ACCU-CAL™ radiometers can measure the intensity of stray or reflected energy to as little as
1 mW/cm2. It is recommended that workers do not exceed 1 mW/cm2 of UVA exposure.

Benefit 3: Measure Transmission Rates Through Substrates

A radiometer can be used to measure the transmission rates of various wavelengths through substrates that sometimes absorb various frequencies of energy. To assure an effective curing process it is critical to measure the light intensity reaching the cure site below any intervening substrate.

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Methods for Testing Worker Exposure to Glutaraldehyde (GLUT)

September 22nd, 2010
 Author: Kyle Rhodes
 

“We have validated high level disinfection of silicone components with Glutaraldehyde chemical sterilant/disinfection solutions. In researching standards or recommendations for safe GLUT residuals in these devices we have found very little information available. OSHA and NIOSH have published or recommended some limited information on worker “exposure” to GLUT in the hospital and the work place. These include values in ppm that are sampled or pulled from the immediate atmosphere and recommendations related to direct contact, which can result in skin irritation issues. Does NELSON have defined tests for measuring patient or worker exposure to devices that have residuals of GLUT?”

 

I would actually take a slightly different approach and have the component tested at a biotesting company, such as NAMSA. In the past I have run evaluations using test method C0020 USP Physicochemical tests, which is a leachables and extractables test in water. This would pick up and identify the value in ppm of residual on the substrate. They do offer a test, C0046 Glutaraldehyde Analysis in Aqueous samples, which can be collected by rinsing the part in water, capturing the water, and sending it in for analysis. I expect that this C0046 test method has defined limits of what is allowable for patient contact, but a call into NAMSA would define the test further.

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What is the Smoke Coming off the Light-Curable Adhesive?

February 19th, 2010
 Author: Dan Hanscom
 

What is that smoke coming off light-curable adhesives
I see smoke coming off the light-curable adhesive…what is it?

 

Before we can answer this question we have to first understand what it’s not.

 

By definition1, it’s not smoke or vapors or outgassing.

 

What you really are seeing coming off of the curing adhesive are fumes generated by the light-curing process. This phenomenon is the result of a very rapid polymerization or chemical reaction that occurs when the liquid adhesive is exposed to the correct wavelength of light. Both heat given off during the reaction (at the molecular level) and heat from the absorption of light energy can, in some instances, result in a small amount of adhesive fumes being emitted before the product has a chance to completely polymerize or cure.

 

Essentially, this phenomenon may emit trace amounts of some of the ingredients (or fractions of the ingredients) contained in the formulation. Please note that the volatilization may or may not be noticeable, but is almost always a very small amount.

 

Are the fumes hazardous? Always consult the MSDS to answer this question. However, if the liquid itself poses a risk to the user, then good manufacturing practices for the particular process may suggest incorporating an exhaust system in the bonding area to remove the fumes during the light-curing step.

 

Definitions1:
Vapor: The gaseous state of a substance that is solid or liquid at temperatures and pressures encountered. NIOSH (National Institute for Occupational Safety and Health) Definition
Fume: A solid condensation particulate, usually of a vaporized metal. NIOSH Definition (This could also be generated from curing our adhesives)
Outgassing: The release of absorbed or occluded gases or water vapor, usually by heating in a vacuum. (Web definition)
Smoke: The vaporous system made up of small particles of carbonaceous matter in the air, resulting mainly from the burning of organic material. (Web definition)

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Venting Your UV Light-Curing Process

June 25th, 2009
 Author: Dan Hanscom
 
 

DYMAX UV Conveyor“Should we install ventilation for our ultraviolet (UV) light-curing process?”

 

Well it depends… We’ve addressed this question from an overall chemical-usage perspective since our answer looks at the “bigger picture”, not just the UV light-curing process.

 

When determining the ventilation requirements for a specific chemical or process, you must consider the following:

 
  1. The size of the room. (In a larger room, you may be able to incorporate normal room ventilation to dilute chemical fumes or vapors below permissible exposure limits)
  2. The volume of chemical being used. (Larger volumes of chemicals may pose greater health and safety concerns)
  3. The physical and health hazards of the specific chemical. (More hazardous chemicals such as corrosives, solvents or flammable liquids may require venting. Always consult the material safety data sheet for information and special instructions)
  4. The chemical state, vapor pressure, and vapor density (i.e. gas, liquid or solid) will help determine whether ventilation is needed, will work, and where to install it if it is needed.
  5. Monitoring chemical levels in the workplace. (If levels are below permissible exposure limits, there may be no need to vent or exhaust) Additionally, if a ventilation system is put into place you must re-evaluate exposure levels to chemical fumes or vapors within the work area. This will determine if additional protection is required.
  6. Atomization of the airborne chemical. (It is always recommended to vent or exhaust a chemical if you are spraying it)
  7. How often the chemical is being used? (When combined with other factors, this could help drive a company’s decision whether to vent or not)
  8. Cost. (this is always an important factor)
 

In the case of a UV light-curing process the answer also depends on the amount of heat generated by the UV light-curing system and the impact it has on the performance of the HVAC system in the area.

 

Ultimately, the decision to install a ventilation system is up to the user of the chemical after a thorough hazard/risk analysis (including workplace monitoring) is completed.

 
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REACH, BPA, DEHP, WEEE???

June 9th, 2009
 Author: Dan Hanscom

 

REACHBPADEHPWEEE??? This is not your mother’s alphabet soup but acronyms for new environmental compliance directives, regulations, and initiatives…

 

As the world shrinks and companies continue to span many continents, we are seeing an increase in global environmental and safety regulations.  Many of these are being initiated in Europe and are spreading throughout Asia and within our own country.  Directives like REACH, WEEE, RoHS, and GHS are driving many companies crazy as they try to understand how the directives affect them.  Initiatives to identify and eliminate DEHP and BPA use in plastics and adhesives are also plaguing many manufacturers.  Very few international companies are immune from these new directives and initiatives.

It’s important to understand each one and how it affects your specific business before investing resources.  In today’s economy companies must invest their resources wisely in order to stay competitive.  It is important to understand the impact of these new regulations and initiatives both financially and from the safety and compliance perspective before moving forward. 

 

What are they?

REACH, a new European Community Regulation on chemicals and their safe use, entered into law on June 1st 2007.  The legislation addresses the Registration, Evaluation, Authorization and restriction of Chemical substances.  The main objective of REACH is to improve the protection of human health and the environment from the risks that can be posed by chemicals used in an industry.

REACH makes industries responsible for assessing and managing the risks posed by these chemicals and provides the appropriate safety information to their users.  The criterion is based on volume (equal or greater than 1 metric tonne) imported into the European Union (EU) or if it is a Substance of Very High Concern (SVHC).  Registration of the substances occurs in phases based on the previously mentioned criteria, with the last occurring in 2018.  Learn more. 

 

WEEE or Waste Electrical and Electronic Equipment is another directive (Directives 2002/95/EC & 2002/96/EC) from the EU which restricts the use of hazardous substances (see RoHS) in electrical and electronic equipment while promoting the collection and recycling thereof.  The recycling program is aimed at re-using electronic waste and encourages consumers to return outdated, broken electronic equipment to the manufacturers at no cost to the consumers.  This eliminates the used electrical and electronic equipment from ever reaching a landfill where it would contaminate the environment with harmful substances that could potentially leech out.  WEEE goes hand-in-hand with RoHS.  Learn more.

 

RoHS or the Restriction of Hazardous Substances (directive 2002/95/EC) works closely with WEEE and is designed to shift manufacturers away from restricted chemicals to safer alternatives.  The EU identified the following substances under RoHS as hazardous with a significant impact to the environment.  They are: 

  • Cadmium (Cd)
  • Lead (Pb)
  • Hexavalent Chromium (CrVI)
  • Mercury (Hg)
  • Polybrominated biphenyls (PBB)
  • Polybrominated diphenyl ether (PBDE )

Additionally, the EU restricted three other flame retardants under 2003/11/EC for their negative impact on human health and the environment.

  • Pentabromodiphenyl ether (PentaBDE)
  • Octabromodiphenyl ether (OctaBDE)
  • Decabromodiphenyl ether (DecaBDE)

Please click here for more information. 

 

GHS or Globally Harmonized System of classifying and labeling of chemicals is a regulation that was created in collaboration with the members of the United Nations (UN). Essentially, this regulation looks at unifying and standardizing all classification and labeling of chemicals so they are globally harmonized.  This means whether you are in Russia, France, Mexico, or the United States the safety information would be communicated in an identical manner through pictograms, hazard warnings, signal words, etc.  Read more from the OSHA website. Each specific country’s adoption of this new standard will vary.  Click here to learn more about your specific country’s adoption schedule for GHS.

 

DEHP and other phthalates

Di(2-ethylhexyl)phthalate (DEHP) is a plasticizer added to polyvinyl chloride (PVC) to make the normally rigid plastic more flexible.  Many companies, especially those in the medical device industry, are requiring suppliers to inform them of DEHP or other phthalate use.  The FDA issued a health warning1 advising the public that DEHP could leech out of PVC and pose a health risk in certain high risk groups.  Specifically, there are concerns pertaining to the effects on the development of the male reproductive system.  More information is available from the FDA website.   

 

BPA

Bisphenol A2 is a key ingredient in the manufacturing of polycarbonate and a constituent within many epoxies.  In recent years, a hypothesis has been advanced claiming that exposure to extremely low doses of certain substances could cause adverse health effects in humans, including disruption of normal hormonal functions.”2 There have been many conflicting studies completed showing that in some cases there is concern to human health but in other studies demonstrating no harmful effects.  Based on some initial tests through the National Toxicology Program (NTP) it appears as though there is “some concern” especially in small children and infants.  To alleviate some of the discrepancies in testing, NTP is requesting additional information from the scientific community pertaining to the health effects of BPA.3  It may be years before we really know whether there is truly a concern with BPA.  It will probably be too late for industry however, who regardless of the outcomes, will have made the switch to BPA alternatives because of these initial concerns.   More information on BPA can be found here.

 

Is there any good from these regulations and initiatives?

While many of these regulations and initiatives may be seen as cumbersome and confusing, some of them really are.  They make sense when you look at the overall picture and what is trying to be accomplished.  Many of the regulations are needed to reduce the impact and bioaccumulation of harmful chemicals in the environment, while minimizing or eliminating any risk to the safety and health of the greater population.

DYMAX ECO Benefits Everyone

DYMAX understands that safe ecologically friendly products benefit our customers, the environment, and us. We have created materials with attributes that lower products costs, life-cycle costs, and ecological impact. Learn more…DYMAX Eco underlines the DYMAX commitment to the environment.

1 Retrieved from the FDA website http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/PublicHealthNotifications/ucm062182.htm

2 Retrieved from the website http://www.bisphenol-a.org/

3 Retrieved from the website
http://www.ehponline.org/docs/2009/117-3/EHP117pa96PDF.PDF
 

 

 

 

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It’s your skin, protect it…

May 5th, 2009
 Author: Dan Hanscom

 

Exposure to chemicals in the workplace is one of the leading causes of skin diseases in the United States. According to the bureau of labor and statistics, skin diseases are more prevalent in the workplace than respiratory illnesses, outpacing them better than 2:1 based on 2006 figures.1

 

Why should you be concerned? Many chemicals are easily absorbed through the skin. In most cases the resulting skin disease, such as contact dermatitis, is caused by direct contact with the chemical. But in some cases, just breathing in the vapors can cause a more serious systemic reaction to the chemical. The resulting effect could show up as a rash or something far worse. The economic impact of occupational skin diseases “may range from $222 million to $1 billion” according to C.G. Toby Mathias’s, MD editorial The Cost of Occupational Skin Disease.2 These costs, however, do not include the effect it has on the quality of life for the individual.

While there are many different effects from dermal exposure to chemicals, this post only describes two of the more common types, contact dermatitis and sensitization. “Contact dermatitis: A skin condition caused by contact between skin and some substance. Includes irritant contact dermatitis (a rash brought on purely by repeated irritation from a substance such as water causing “dish pan hands”) and allergic contact dermatitis (involving a specific sensitivity or allergy to a specific substance such as poison ivy).”3

Chemical sensitization is caused by an allergic reaction the body can develop to many chemicals. This allergy may exist already or may develop following a few days, weeks or even years of exposure. Once a person becomes sensitized, even very small amounts of chemicals can bring out an allergic reaction.”4

While dermal exposure to chemicals is a problem for many employers, there is good news.
It’s preventable!

 

How is it preventable? Many options exist to protect employees from chemical exposure such as employing a variety of engineering and administrative controls, or through the use personal protective equipment (PPE). Substituting the problem chemical with a non-hazardous alternative will remove the potentially harmful effect. When substitution is not possible or feasible, installing protective controls to minimize or eliminate contact with the chemicals is the next best option. Lastly, personal protective equipment, which may or may not be used in conjunction with other types of safety controls, will protect or cover any exposed skin. PPE like gloves, disposables sleeves, coveralls, chemical suits, goggles, and face shields, etc., will not eliminate the hazard but will provide personal protection from them. One key component to minimizing or eliminating dermal exposure to chemicals is training. Training should include information on the hazards, effects, and how to protect employees (from PPE use and selection to the use of engineering controls).

 

What happens if I get a chemical onto my skin? The immediate solution is to wash your hands with soap and water. You should never wash your hands with an organic solvent for this could exacerbate a skin condition and be absorbed quickly into your circulatory system, potentially causing other harm.

Before you work with any new chemical you should consult the material safety data sheet (msds) before using. This document will provide information on the hazardous effects, routes of entry, PPE or other controls to protect you from the chemical. It will also provide information on how to treat an exposure to the chemical correctly and safely.

As defined within OSHA’s (Occupational Safety and Health Administration) Hazard Communication Standard 29 CFR 1910.1200, it is your legal “right to know” about the hazardous chemicals you may be exposed to at your place of employment.

Each individual or cumulative effect has the potential to adversely affect a company and their employees. Only through a proactive effort to prevent contact with hazardous chemicals through the proper use of engineering and administrative controls, and personal protective equipment will a company minimize or eliminate dermal exposure to chemicals. This will ensure the safety and health of their most valuable asset, their employees.

 

1 Retrieved from the website http://www.osha.gov/SLTC/dermalexposure/index.html
2 C. G. Toby Mathias, MD Arch Dermatol. 1985;121(3):332-334.
3 Retrieved from the website http://www.medterms.com/script/main/art.asp?articlekey=20442
4 Retrieved from the website http://www.bacweb.org/safety_training/sh_tips.htm

 
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The Nose Knows… or Does It?

April 1st, 2009
 Author: Dan Hanscom

 

True or False? - The adhesive smells so it must be harmful. 

For the most part… False.

 

The majority of people have a sense of smell that is acute and sensitive enough to detect odors in the parts per million (ppm). Ozone, for example, can be detected at concentrations as low as 0.01 ppm.  However, it is not dangerous until the 8-hour time-weighted average (TWA) for the permissible exposure limit (PEL) of 0.1 ppm is exceeded.

 

On the other hand, isocyanates, which are used in many single and two-part polyurethanes have poor olfactory warning properties.  This means that if a person detects its odor he has already exceeded the OSHA1 or ACGIH2 exposure limits.  For example, one form of isocyanate, TDI’s (toluene 2, 4-diisocyanate) has a PEL of 0.02 ppm over an 8-hour TWA, and due to the chemical’s poor warning properties a person’s exposure would exceed this limit if an odor is detected. 

 

In some situations when using a solvent-based adhesive, such as one that contains methylene chloride, employers should establish safe use procedures that incorporate engineering controls and the use of personal protective equipment to minimize exposure. Even better would be to replace the solvent-based product with a solvent-free adhesive.  In the case of most solvent-containing materials, the nose will provide ample warning to an employee that an odor/exposure is detected,  but it will not tell them if it’s harmful or if exposure limits have been exceeded.

 

The best way to learn more about a particular chemical or adhesive is to consult the material safety data sheet (MSDS).  The nose should never be used to determine if a product is harmful.

 

Why does this new adhesive smell so much more than our current product? 

 

The short answer is that a person’s sense of smell, through prolonged exposure, becomes desensitized to the current odor.  When a different odor is detected your nose smells only the new odor. 

 

Additionally, people develop olfactory fatigue which is a temporary inability to detect a particular odor. For example, when you enter a restaurant and smell freshly cooked garlic, this odor is only noticed for a short period of time.  When a new odor is introduced, lets say, freshly baked cookies, your olfactory senses detect the new aroma but not the garlic smelled earlier.

 

After a prolonged exposure to a new adhesive, an employee will also become desensitized to this material and if you were to switch back to the old adhesive this one would smell a lot worse.

 

Does the new adhesive smell worse?  Maybe, but it is more likely that it’s just different and your nose has yet to become accustomed to it.

 

Photo courtesy of  http://www.freeimages.co.uk/index.htm

1 Occupational Safety and Health Administration

2 American Conference of Governmental Industrial Hygienists

 


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Protect yourself from the hazards of industrial ultraviolet (UV) light exposure.

March 19th, 2009
 Author: Dan Hanscom

 

Ultraviolet (UV) light is a form of electromagnetic energy invisible to humans. UV light falls below visible light on the electromagnetic spectrum so it does not trigger the natural defenses of the eyes, such as pupil dilation experienced with bright visible light.  For this reason, it is important to use personal protective equipment and not to disable any safety controls designed into the UV light source.  Many people often mistake the bright light coming off these systems as harmful, but in reality what they are seeing is harmless visible light. 

 

While all UV light has the potential to harm an employee when used carelessly, the shortwave UV energy (UV-C) poses the greatest risk to those using these light sources.  Most UV sources sold in the light-curable adhesive market incorporate the safer UV-A energy.  It is important to review the specifications for your own UV source before using it. 

 

Ultraviolet light exposure is the primary cause of melanoma.  Most cases of melanoma, however, are preventable by protecting yourself from effects of UV exposure. 

 

In industrial settings UV exposure is often misunderstood, but it is in these settings where manufacturers have the greatest control over a worker’s health and safety.

 

UV Conveyor Curing Clamshells

Industrial UV light-curing systems are often designed with safety or engineering controls built into them.  These controls, such as shielding, safety interlocks, intuitive design, and light-absorbing plastics, allow operators to use them without ever exposing themselves to harmful ultraviolet light. Teaching employees how to protect themselves from UV exposure and training them to work safely around these UV systems will minimize any potential risk of harm. 

 

Curing Equipment

A device called a radiometer can be used to demonstrate the amount of UV light an employee is exposed to while operating a UV curing system.   Taking the radiometer’s sensor and holding it near a person’s exposed skin while the unit is on, and then comparing this to what a person is exposed to outside on a sunny day, will show the individual is experiencing greater exposure from the sun.  It is important to match the radiometer to the UV wavelength being measured.

 

When used properly and in conjunction with personal protective equipment and training, industrial UV light sources are safe and easy to use.

 

 

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