Draft Code of Practice: safe handling of dichloromethane-based paint strippers, chapter 1

1. Code of Practice for Paint Stripping Activities at Commercial Furniture Restoration Facilities

1.1 Applicability

Part 1 of the Code of Practice applies to furniture restoration facilities that use:

  1. gel-based paint stripper that is brushed onto the furniture surface; and/or
  2. liquid-based paint stripper that is used in a flow-over system.

Furniture restoration facilities may also use dip tanks to strip paint. However, this practice is not widespread. A discussion of work practices applicable to furniture restoration facilities that use dip tanks is provided in Part 2 of the Code of Practice (Section 2.2), which identifies work practices for metal part paint strippers that use dip tanks.

Many of the work practices outlined below are designed to reduce the dichloromethane evaporation rate of the paint stripping formulation. Reducing the evaporation rate serves to reduce dichloromethane emissions. In addition, minimizing the evaporation rate and emissions will serve to reduce the amount of wasted paint stripper, thus reducing a facility’s overall operating costs.

Not all work practices identified in this section are appropriate for every facility. Each furniture restoration facility should review the Code and implement those work practices appropriate for its specific situation.

1.2 Work Practices - General

The work practices outlined in this section apply to furniture restoration facilities that use either gel or liquid-based paint stripper.

1.2.1 Use Methods other than Paint Stripping to Restore Furniture Items

It is possible to avoid paint stripping entirely when restoring some furniture items. Some furniture can be simply sanded or washed to remove grease before refinishing. Other furniture items may be re-coated without paint stripping, or simply waxed and buffed. Applying lacquer thinner mixed with shellac over the existing coating is another option. For some furniture items, avoiding paint removal can minimize potential damage that may occur during the restoration process and reduce the cost of the restoration project. The potential to avoid paint stripping will depend on customer requirements and the purpose of the restoration project.

1.2.2 Use non-Dichloromethane-Based Paint Stripping Alternatives When Feasible

Alternatives to dichloromethane-based paint strippers are available. However, these alternatives may contain hazardous materials and care should be exercised when using them. Workers should familiarize themselves with the properties, as well as advantages/disadvantages, of these alternatives. Workers should read the material safety data sheets and any other safety and handling information before using any paint strippers. The material safety data sheets contain information on the appropriate personal protective equipment (e.g. approved respirators, gloves, safety goggles, full face shields, protective clothing, etc.).

Coats of paint that are easily removed should be first stripped from the furniture item manually using a scraper or sandpaper prior to applying the paint stripper. Stripping excess coats of paint with a scraper or sandpaper will reduce the quantity of paint stripper required to remove the remaining coats.

1.2.3 Use Paint Strippers with Lower Dichloromethane Content, When Possible

Paint strippers used by furniture restoration facilities generally contain approximately 70-90% dichloromethane. Whenever possible, use paint strippers that have a lower dichloromethane content.

Paint strippers with lower dichloromethane content will not in all instances result in reduced dichloromethane emissions. Therefore each facility should evaluate its own particular situation and the potential benefits, if any, of using paint strippers with a lower dichloromethane content.

Paint strippers with lower dichloromethane content may not remove the paint from furniture items as rapidly as paint strippers with a higher dichloromethane content. Therefore, use lower content dichloromethane-based paint strippers when time allows or when additional quantities of the paint stripper will not be required, which would offset the benefits of using a lower content dichloromethane-based paint stripper.

1.2.4 Clean the Furniture Item Prior to Stripping

Materials caught in crevasses may prevent the paint stripper from removing all of the paint from the furniture surface. Therefore, additional applications of paint stripper may be required in order to remove all of the paint completely. Cleaning furniture items will also help to avoid contaminating the paint stripper (i.e., in a flow-over system) which reduces the product’s effectiveness. Sanding can also be used to clean the furniture item and to break down the surface coating allowing easier penetration of the paint stripper.

1.2.5 Use Paint Strippers that Contain a Wax Additive

The paint stripping formulations used should contain a wax additive that hardens on the top of the paint stripper when applied. When dichloromethane and other solvents evaporate from the paint stripper, the solution cools at the surface such that the wax hardens and forms a barrier. This wax barrier reduces contact between the dichloromethane in the paint stripper and the surrounding air, thereby reducing the evaporation rate of dichloromethane. The surface should be left undisturbed for a certain length of time in order to allow the wax barrier to form.

1.2.6 Conduct Paint Stripping Activities Within the Optimal Temperature Range, Whenever Possible

Use paint stripper within the optimal temperature range, usually between 13°C and 18°C, whenever possible. Stripping paint in this temperature range allows for a rapid reaction time and minimizes evaporation and premature drying of the paint stripper. Applying paint stripper below 13°C may result in a slow reaction rate between the dichloromethane and the coating. Dichloromethane may evaporate before the coatings have been stripped from the wood substrate. In addition, the wax barrier may solidify completely, thereby reducing the effectiveness of the paint stripper. Applying paint stripper at temperatures above 18°C may result in evaporation of the dichloromethane before it has reacted with the coatings. High temperatures also reduce the ability of the wax barrier to form.

Minimizing evaporation loss of dichloromethane by using the paint stripper at ambient temperatures of between 13°C and 18°C can reduce both the amount of paint stripper needed and decrease the time required for the paint stripper to act.

If working outdoors, apply paint stripper in cool, shaded areas. Avoid applying paint stripper in direct sunlight. The dichloromethane in the paint stripper may dry too quickly if the surface being stripped is heated or exposed to sunlight. An additional application of paint stripper may then be required. Paint strippers maintain their effectiveness on cool, shaded surfaces.

1.2.7 Test the Surface Before Applying the Paint Stripper

Test the surface of the furniture item to determine the type of coating to be removed and to ensure that an appropriate paint stripping formulation is used. Commercial testing devices have been developed; these indicate whether the coating to be removed from the furniture item is nitrocellulose lacquer, polyurethane, or some other type of coating. These devices work by changing colour when they are applied to the furniture coating. A small section of the furniture item is usually tested. Applying alcohol or lacquer thinner to the furniture item can also indicate the type of coating that has to be removed and indicate whether the paint stripper will be effective. For easily removable coating(s), low or non-dichloromethane content paint strippers can be applied.

1.2.8 Cover Surface Areas Coated with Paint Stripper

The use of a cover will reduce the amount of contact between the dichloromethane in the paint stripper and the surrounding air as well as allow a longer reaction time between the paint stripper and the coatings. This will slow the dichloromethane evaporation rate and slow the drying of the paint stripper. As a result, using a cover may reduce the need for additional applications of paint stripper. Use wax paper, nylon, cellulose (paper)-based covers or plastic sheeting (e.g. polypropylene), which is chemically resistant to dichloromethane and other organic solvents. Test the reaction between the paint stripper and the selected cover prior to using it on the furniture items.

This work practice may be more suitable for: (i) furniture items with flat surfaces, such as tables; and (ii) coats that have proven difficult to remove and will require a long penetration time.

1.2.9 Optimize Ventilation with Consideration for Workplace Exposure

Ventilation is important for controlling worker exposure to dichloromethane vapors. However, creating air disturbances in the work area can increase worker exposure and solvent emissions by accelerating evaporation. The amount of ventilation applied in the workplace should be appropriate to address workplace exposure issues, but should not be excessive to create air disturbances.

1.3 Work Practices - Hand Stripping (Gel-Based Paint Stripper)

The work practices outlined in this section apply to furniture restoration facilities that use gel-based paint stripper. Gel-based paint strippers are typically applied manually with a brush.

1.3.1 Brush Paint Stripper onto the Furniture Surface in One Direction, Using as Few Strokes as Possible

Paint strippers should not be applied to the furniture item using back and forth strokes as this disturbs the wax seal that forms on the surface. When applying the paint stripper, minimize the number of strokes over the surface, since this also disturbs the wax seal. Disturbing the wax seal results in exposure of the dichloromethane in the paint stripper to the surrounding air, which increases evaporation rate of the stripper. Excessive brushing will also result in the entrainment of air in the paint stripper, which reduces the contact between the dichloromethane and the surface area to be stripped. Excessive brushing will reduce the effectiveness of the paint stripper and increase the exposure of workers to its emissions.

1.3.2 Apply Paint Strippers to Workable Surface Areas

Paint stripper should be applied in small, workable areas that will allow the paint to be scraped off before the paint stripper dries. The dichloromethane and other solvents in the paint stripper will eventually evaporate, causing the applied paint stripper to dry. Should this happen prior to removal of the paint surface, an additional application of paint stripper will be required. It may be more difficult to remove the paint, once a coat of paint stripper has been left to dry on a piece of furniture. Stripping furniture in segments will prevent this from happening. The size of the workable area will depend on the experience of the individual applying the paint stripper.

Applying stripper using the manufacturer’s recommended rate will minimize the number of instances of paint stripper drying prior to removal. Although the amount required will depend upon the item in question and how many coats must be removed, as a guide, each gallon (3.8 liters) of paint stripper should be able to strip about 75 to 100 square feet of surface.

1.3.3 Leave the Paint Stripper on the Surface for a Sufficient Length Time

To avoid wasted paint stripper, ensure that the paint stripper has penetrated the coating sufficiently before attempting to scrape off the substance. Paint stripper that is removed before fully penetrating the furniture coat(s) will not allow full removal of the coat(s). Therefore, another application of paint stripper may be required. Test the coat often to determine whether it is ready to be removed. An indication that the paint stripper has penetrated the paint and is ready to be scraped off can vary depending on the coat, but may include bubbling of the surface coat or flaking or sheeting of paint when tested.

1.3.4 Remove Paint Stripper from Storage Containers in Small Quantities

Unused gel-based paint stripper is not typically returned to its storage container once the stripping job is complete. Due to evaporation of the dichloromethane and other solvents, the returned paint stripper would not have the same composition and properties as the paint stripper in the storage container. Therefore, unused paint stripper is typically disposed of. Removing small amounts from the storage container as required will minimize the quantity of paint stripper wasted.

1.3.5 Capture and Reuse Paint Stripper Where Applicable

Stripping vertical furniture surfaces or surfaces that are close to the floor may cause paint stripper to drip onto the floor. If these drippings are caught on trays (e.g. pie plates placed under the furniture legs), they can be reapplied to the surface being stripped. This will reduce the overall quantity of paint stripper used.

1.3.6 Use High-Viscosity (i.e. thick) Paint Strippers

The use of high viscosity paint strippers on vertical surfaces reduces drippings from the surface being stripped, such that additional applications of stripper may not be necessary. Liquid-based paint strippers should not be brushed onto vertical furniture surfaces as the paint stripper will not form a film and will run off the surface before it can react with the coating.

1.3.7 Scrape Layers of Paint from the Furniture Starting at the Top

When removing the paint stripper and coats of paint, always begin the scraping process at the top of the furniture item being stripped and proceed downward. Starting the scraping process at the top of the furniture item prevents the potential for re-coating of previously stripped area with paint or paint stripper scrapings. This may reduce the amount of paint stripper used.

1.4 Work Practices - Flow-over (Liquid-Based Paint Stripper)

The work practices outlined in this section apply to furniture restoration facilities that use liquid-based paint stripper, typically applied using a flow-over system.

1.4.1 Strategically Plan Paint Stripping Activity

By strategically planning paint stripping activities, exposure of the paint stripper left in the flow-over tank (or the unsealed storage container) to the surrounding air can be minimized. Paint stripping activity can be scheduled so that all of the furniture items to be stripped for the day are dealt with sequentially (e.g. in the morning). Therefore, the paint stripper contained in the flow-over tank storage container can be sealed after the last item has been stripped. If paint stripping activities occur throughout the day, paint stripper in the flow-over tank will be exposed to the atmosphere for an extended period of time, thus increasing the dichloromethane evaporation rate and emissions and potentially decreasing the efficiency of the paint stripper as its composition changes.

1.4.2 Collect Paint Chips Entering the Recirculating System in a Strainer

If a pump is used to circulate paint stripper, collect the paint chips that flow through the drain in the flow-over tank and into the circulation system in a strainer. A strainer can catch the paint chips that flow through the flow-over tank drain. These paint chips can then be removed from the strainer. The dichloromethane should be allowed to drain separately into a paint can or similar collection device. The paint stripper that is captured in this system can then be recycled into the flow-over system.

1.4.3 Apply Paint Stripper Close to the Drain for the Recirculating System

The furniture item that is placed in the flow-over tank should be located near the drain for the recirculating system. This will ensure that paint stripper poured over the furniture item has a minimum distance to travel to reach the drain and the circulation system. This will reduce the length of time the paint stripper is exposed to the surrounding air and, consequently, reduce dichloromethane emissions.

1.4.4 Introduce Paint Stripper into the Flow-over Tank By Pouring it Into the Circulation System

When introducing paint stripper into the flow-over system, pour paint stripper into the container that captures the paint stripper draining out of the flow-over tank. A hose attached to this container draws paint stripper up to be poured over the furniture item being stripped. This process is designed to minimize disturbance to the paint stripper and its exposure to the surrounding air. If paint stripper was poured directly into the flow-over tank, then it would have greater exposure to the surrounding air. In addition, pouring paint stripper directly into the flow-over tank rather than the container would entail considerably more splashing.

1.4.5 Circulating Pumps Should be Kept Off When the Flow-over System is not in Use

Turn off pumps that circulate paint stripper in the flow-over system when the system is not in use. Turning circulation pumps off will stop the flow of the paint stripper and therefore halt exposure of the paint stripper to the surrounding air.

1.4.6 Keep the Hose End Close to the Furniture Item Being Stripped

Keeping the hose end close to the furniture item being stripped will reduce the distance that the paint stripper has to travel and therefore reduce its exposure to the surrounding air. The distance between the hose and the furniture item being stripped will depend on the item. For instance, the hose end may be held higher when stripping a table so as to disperse the paint stripper more efficiently.

1.4.7 Allow Paint Stripper to Drain From the Furniture in the Flow-over Tank Before Rinsing

Before removing furniture from the flow-over tank and taking it to the rinse area, let the furniture item drain completely (i.e. the paint stripper has stopped dripping). In addition to rotating furniture above the flow-over tank, use a brush to help return excess paint stripper to the flow-over tank. Maximizing the amount of paint stripper returned to the flow-over tank will reduce the quantity lost in the rinsing area. This will also reduce the quantity of paint stripper purchased. The furniture items can be physically manipulated or brushed in order to assist in removing excess paint stripper. Flat surfaces such as a tabletop can be leaned against the side of the flow-over tank so that the paint stripper will drain back into the flow-over tank.

1.4.8 Apply Recycled Paint Stripper to Furniture Items with Numerous Coats

Apply recycled paint stripper to furniture items that have several layers of coating in order to remove most of the paint. Then apply new paint stripper to remove the remaining paint. Using this process will reduce the amount of paint stripper contaminated with paint chips, which reduces its effectiveness. The first layers may be easier to remove and therefore the lower-strength, contaminated paint stripper can be used. New paint stripper should be used on furniture items with light coatings or that are nearly bare.

1.4.9 Use Solvent Recovery Companies or In-House Recycling Technology

Paint chips and sludge can be drained at the furniture restoration facility to recycle paint stripper, or the paint chips/sludge can be sent to the solvent recycling company at various stages of the recycling process. For instance, the paint chips/sludge can be sent to the recycler immediately after capture or they can be sent after the furniture restoration facility has collected as much of the paint stripper as possible. The furniture restoration facility can determine at which stage it would be in their best interest to send the paint chips/sludge to a solvent recycler.

Solvent recovery technology is available to extract dichloromethane contained in paint chips removed from furniture at restoration facilities. These solvent recovery systems are generally only used after the collected paint chips have been put through the recycling system at the furniture restoration facility, which usually consists of allowing paint stripper to drain by gravity from the collected paint chips. The paint chips are then introduced into the solvent recovery system to capture the remaining dichloromethane. Health and safety issues surrounding the use of solvent recovery technology should be evaluated prior to its utilization by furniture restoration facilities.

1.4.10 Ensure that the Paint Stripper Does not Dry on the Furniture Item Being Stripped

Do not allow paint stripper to dry on the surface of the furniture item being stripped. Scrape all paint off the furniture item when the paint stripper coating is wet. The dichloromethane and other solvents in the paint stripper will eventually evaporate, causing the applied paint stripper to dry out. Should this happen prior to removal of the paint surface, an additional application of paint stripper will be required, resulting in more emissions.

1.4.11 Drain Paint Stripper From the Flow-over Tank When the Tank is Not in Use

Draining paint stripper from the flow-over tank and storing it in a sealed container will reduce contact between the paint stripper and the surrounding air. This work practice should result in less dichloromethane evaporation than simply covering the flow-over tank when the system is not in use. However, covers may be more practical when paint stripping activities have ceased for only a short period of time (e.g. lunch break).

1.4.12 Cover the Flow-over Tank When not in Use

For those furniture restoration facilities that do not use a circulating system, a tight fitting cover should be placed on top of the flow-over tank at all times, except when the system is in use. This cover will reduce contact between the paint stripper and the surrounding air, which will minimize the evaporation of dichloromethane.

1.4.13 Reduce the Surface Area of the Flow-over Tank

Flow-over tanks come in various sizes (height; width; length). Using a deeper flow-over tank that is shorter and narrower will reduce the surface area of the exposed paint stripper in the flow-over tank. Minimizing surface area will reduce the amount of paint stripper in contact with the surrounding air, thus reducing emissions.

1.5 Paint Stripper Handling and Storage

Ship paint stripper in closed, airtight containers.

Keep the lids on paint stripper containers tightly closed at all times. Re-fasten paint stripper container lids immediately after paint stripper is removed from the container.

Store paint stripper containers in a cool, dry, well-ventilated location. Exposure to high temperatures or to the sun may cause paint stripper containers to leak or swell.

Try to remove as much of the paint stripper from its storage container as possible before disposing of the storage container.

When filling smaller vessels from the larger paint stripper storage container, keep the tap near, if not in, the entry hole to reduce exposure to the surrounding air.

1.6 Waste Handling and Disposal

Dispose of empty, non-returnable containers immediately using an approved method. Treat the containers as waste or hazardous waste as appropriate to the residues in the container.

If a container is to be used to accumulate material for recycling or waste disposal, it should be stored with lids and all other openings tightly sealed after every addition.

Ship waste or recyclable materials in closed, airtight containers.

After the paint stripping process, collect materials soaked with paint stripper and transfer them immediately to the designated waste storage container. Dispose of this waste through a certified waste disposal or processing company. Suppliers of paint stripper may have a collection service for contaminated paint stripper. Contact the local county, municipal or provincial government authority for instructions on disposal.

It may be possible to wipe the stripped surface down with a damp (with water or lacquer thinner) cloth, steel wood pad or stiff bristle brush instead of hosing down the surface. This will avoid the introduction of paint stripper residue and dichloromethane into the municipal wastewater system. Place the used scrubbing materials (e.g. brush, cloth, etc.) in a sealed storage container after use and dispose of them according to current municipal and other environmental requirements.

1.7 Record-keeping

Keep the information required in this section for 3 years to track paint stripper use and to help develop an internal dichloromethane emission reduction system.

Record specific actions implemented to reduce the quantity of paint stripper used or the quantity of dichloromethane emissions. These actions may be contained in this Code of Practice or may be developed by the facility. Also record the date that these actions were initiated at the paint stripping facility.

Record the quantity of dichloromethane, as contained in paint strippers, used per year.

Commercial paint strippers should ask the paint stripper manufacturer or their supplier to track the facility's annual paint stripper purchases as well as the dichloromethane content of that product. Running totals on invoices may be provided, indicating the total paint stripper and dichloromethane usage for the year to date.

Should the manufacturer or supplier be unable to provide a running total of annual dichloromethane consumption, this amount may be estimated. To determine the quantity of dichloromethane used per year, keep records on the quantity (volume) of dichloromethane-based paint stripper purchased per year and its percentage dichloromethane content. Product information sheets for the paint stripper will contain either a range of the dichloromethane content in the paint stripper (e.g. 80-85%), or the actual content (e.g. 80%). Use the value given to calculate total dichloromethane consumption for the year.

For instance, 10 drums, each 205 litres, of dichloromethane-based paint stripper were purchased during the year, with average dichloromethane content of 70%. Therefore, 10 X 205 = 2 050 litres of paint stripper were purchased. With an average 70% dichloromethane content, a total of 1 435 litres (2 050 litres X 0.70) of dichloromethane were purchased during the year.

Record the quantities of dichloromethane containing waste along with the details of the waste disposal and/or recycling company and method of disposal or recovery. Subtract this quantity from purchases to estimate releases.

If the ownership of a commercial paint stripping operation is transferred, transfer records related to paint stripper use and reduction measures implemented to the new owner along with a copy of this Code.

1.8 Training

Train individuals responsible for paint stripping to use the specific work practices contained in this Code of Practice. In addition to an initial training period, give all operators an annual refresher course. The training provided should teach the skills necessary to implement the work practices in this Code of Practice.

Train the individuals responsible for paint stripping to implement the recommended paint stripper application instructions provided by the manufacturer.

Employees in the paint stripping facility should review material safety data sheets, other health and safety documents, and any paint stripper product literature provided by suppliers. Updated information should be requested from the supplier in order to determine the quantity of dichloromethane in products.

Consider enrolling in a paint stripping course (e.g. Fanshawe College in Ontario currently offers an 8 week course on furniture refinishing).

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