Exterior vs. Interior Paints

[mechman]

I've stated this many times now when I first bought the Dulux Exterior paint to compare to Black Widow. I also see that some folks are still recommending exterior paints. Bad idea!

Exterior paints contain many things that aren't meant for interior use. They contain mildicides, fungicides, pesticides, etc.

From Bob Vila:

One of the most important things to be aware of is that paint is formulated for either interior use or exterior use, and they have different properties: Interior paint is formulated for: Scrubbability and stain resistance; Good hiding ability; Splatter resistance; Easy touch-up. Exterior paint is formulated for: Color retention; Resistance to fading; Flexibility to withstand expansion and contraction due to weather; To provide a mildew resistant coating; Resistance to tannin bleed. Don't think that you should use exterior paints indoors on the assumption that it is "tougher". In fact, some of the highest-grade exterior paints can be worse to use indoors than a lower-quality interior paint.

From True Value:

Health Risks of Exterior Paint Used in Basement

Question:
What is the impact of using exterior paint inside? We used the True Value All Weather Exterior Paint on the inside of a basement. Should there be any difference in smell after 2 years? Is there any reason that this would be harmful? What is the difference between the interior and exterior paints? Is it a health problem?


Answer:
Exterior paint is not durable for inside use. It may chalk excessively and/or the paint would not stick to the surface if it needs to be repainted. Exterior paint also contains mildewsides/fungicides that may smell when there is high humidity. It can even pose a health hazard due to the greater concentration of these mildewsides that are not normally used inside. Exterior paint used indoors may also worsen allergies.

From Natural Handyman

Dear NH,
Is there any reason why I can't use exterior paint on the interior walls?
BM

Yes, there is. Exterior paint contains certain fungicides and UV protective additives that are not approved for interior use. Because of the extreme conditions exterior paints are designed to endure, the strength of the preservative chemicals used may be unhealthy in closed inside areas.

This begs the question, "Why do you want to use exterior paint inside your home?" If you are looking to get some of the qualities of exterior paint, such as mildew or water resistance, there are interior paints and additives that can do the job just fine.

For example, there are special bathroom and kitchen paints that have very durable, eggshell finishes plus tremendous mildew resistance. There are also additives, known as mildewcides, that are designed for interior use. They can be added to any paint, even flat ceiling paints and texture paints, to make them more "bathroom friendly" and mildew resistant.

Do not use an exterior paint for an indoor screen! Exterior Paints are just that! Exterior!

This important service announcement brought to you by....

mech

[mechman]

And this from CIL:

Q: Can I use exterior paint inside?

A: We do not recommend that you use an exterior labeled paint for interior use. Exterior paints are designed for specific use on exterior surfaces, hence performance and film integrity may be compromised if used on interior surfaces. Additionally, exterior paints typically have included in their formulation mildewcides, to resist the growth of mildew on the dry paint film, and the level of mildewcide in the exterior paint may be above the level recommended for interior use.

From Lowe's:

When painting indoors, use paint marked as "Interior" or "Interior/Exterior." Exterior paint is not for indoor use. Plus it doesn't dry as quickly and has a stronger odor — an important factor inside the house.

From House Painting Info:

Paints that are dedicated for exterior use have concentrated mildewcides and fungicides that could have heath risks if used indoors. Plus, exterior paints have more VOC’s, which means the paint will have a potent smell when compared to its interior counterparts.

Exterior paints, especially acrylics, are designed to fast dry and resist the worst that the environment can offer. Because of this, exterior paints won’t easily flow out smoothly on a surface and will more difficult to use. Many quality interior paints have the same great attributes as exterior paints without the health risks or problems of exterior paints.

I hope this helps keep people safe!

mech

[Harpmaker]

Most excellent thread!

Even if exterior paints were better for screens it wouldn't be worth the health risk or stink.

Thanks mech!

[mechman]

From Dulux MSDS on the exterior acrylic latex paint:

TOXICOLOGICAL INFORMATION (ANSI Section 11)

Supplemental health information : Contains a chemical that may be absorbed through skin.
Excessive inhalation of fumes may lead to metal fume fever characterized by a metallic taste in
mouth, excessive thirst, coughing, weakness, fatigue, muscular pain, nausea, chills and fever.
Other effects of overexposure may include toxicity to liver, kidney, lungs, central nervous
system, reproductive system.

Carcinogenicity : Contains crystalline silica which is considered a hazard by inhalation. IARC has
classified crystalline silica as carcinogenic to humans (group 1). Crystalline silica is also a
known cause of silicosis, a noncancerous lung disease. The national toxicology program (NTP)
has classified crystalline silica as a known human carcinogen. The international agency for
research on cancer (IARC) has classified carbon black as possibly carcinogenic to humans
(group 2b) based on sufficient evidence in animals and inadequate evidence in humans. In a
lifetime inhalation study, exposure to 250 mg/m3 titanium dioxide resulted in the development
of lung tumors in rats. These tumors occurred only at dust levels that overwhelmed the animals'
lung clearance mechanisms and were different from common human lung tumors in both type
and location. The relevance of these findings to humans is unknown but questionable. The
international agency for research on cancer (IARC) has classified titanium dioxide as possibly
carcinogenic to humans (group 2b) based on inadequate evidence of carcinogenicity in humans
and sufficient evidence of carcinogenicity in experimental animals.

Reproductive effects : A study conducted by NTP, using a continuous breeding protocol, demonstrated that
diethylene glycol in drinking water at a concentration of 3.5% (6.1 G/kg/day) resulted in decreased
fertility and reproductive performance in mice. These effects were not seen in the lower dose levels
evaluated. Since the exposure resulting from incidental contact is likely to be lower by several degrees
of magnitude and the route of exposure used in this study does not reflect a likely route from
occupational or consumer use the significance of these findings to humans is uncertain.

Mutagenicity : No mutagenic effects are anticipated

Teratogenicity : Some laboratory test results have shown ethylene glycol to be an animal teratogen. However,
an expert panel convened by the national toxicology program's center for the evaluation of risks to
human reproduction (cerhr) conducted a review of the scientific literature and concluded that ethylene
glycol does not present a significant concern with respect to developmental and reproductive toxicity in
humans.

Compared to an interior latex:

TOXICOLOGICAL INFORMATION (ANSI Section 11)

Supplemental health information : No additional effects are anticipated

Carcinogenicity : In a lifetime inhalation study, exposure to 250 mg/m3 titanium dioxide resulted in
the development of lung tumors in rats. These tumors occurred only at dust levels that
overwhelmed the animals' lung clearance mechanisms and were different from common human
lung tumors in both type and location. The relevance of these findings to humans is unknown
but questionable. The international agency for research on cancer (IARC) has classified
titanium dioxide as possibly carcinogenic to humans (group 2b) based on inadequate evidence
of carcinogenicity in humans and sufficient evidence of carcinogenicity in experimental
animals.

Reproductive effects : No reproductive effects are anticipated

Mutagenicity : No mutagenic effects are anticipated

Teratogenicity : No teratogenic effects are anticipated

mech

[benven]

How about you compare it to the paint you are recommending:

TYPICAL ANALYSIS 94783
C.A.S. NO. INGREDIENTS
7732-18-5 Water
13463-67-7 Titanium Dioxide
22708-90-3 Clay
25035-69-2 Acrylic Copolymer
1317-95-9 Silica
107-21-1 Ethylene Glycol
14808-60-7 Crystalline Silica

The same ingredients as you cite as being in the exterior paints that cause all sorts of crazy medical issues.. And to boot, it contains clay! I see no difference. And besides, who is going to drink a 3.5% solution of ethylene glycol?

[mechman]

No Ben. There's a huge difference. And that is in both quantity and ingredients. I've posted the MSDS sheets above your post from both and interior and an exterior. Did you read that? The toxicological analysis is very different for the two. You can say that this paint has the same ingredients as the other but that's a very misleading statement. And of course there's still the matter of fungicides and mildewcides, which is lacking from what you've listed.

mech

[benven]

I read what you wrote. Did you read what I wrote? Those ingredients were for the Valspar paint you are recommending as a base for BW. The exterior paint MSDS you cited contains titanium dioxide, ethylene gylcol, and silica. So does the Valspar paint. Therefore, the same materials, the same side effects. You can't grandstand and then minimize what you stated. They are the same ingredients. As far as mildicides and fungicides are concerned, they will probably be copper or quat based materials. Not volatile components. Again, you need to ingest or snort the paint thru a straw to be affected by these materials. Remember oil based paints?? VOCs thru the roof. Interior and exterior latex based paints have much lower VOCs. This is the component that gases off and can potential cause health effects. I think this whole thing has been blown out of proportion. I was just merely highlighting the fact that interior latex paints have the same basic ingredients as exterior latex paints. And I have a kid who is highly asthmatic and anaphylatic. He paints right next to me and has never been affected by the use of Behr 4850.

[mechman]

Again Ben, I apologize. I guess the MSDS' and the numerous sources cited know very little.

Thread closed.

mech

[mechman]

Just trying to keep this in people's minds before they try to use an exterior paint indoors.

[mechman]

The main reason I'm stressing this is that I guess someone thinks that using an exterior paint inside is a good idea. If you put 3 coats on a 100" screen you'll be near 75 square feet of chemicals invading your indoor air quality!

http://www.epa.gov/iaq/homes/hip-painting.html

Painting and IAQ

Read "The Inside Story: A Guide to Indoor Air Quality"

energy star

There are many factors to consider before beginning a painting project. Special care should be taken when sanding a surface to prepare for painting due to the dust released into the air. The dust may contain lead particles, if the surface contains lead-based paint. Exposure to excessive levels of lead could affect a child's mental growth, and interfere with nervous system development, which could cause learning disabilities and impaired hearing. In adults, lead can increase blood pressure. Unless a lead-based paint inspection shows it doesn't, you should treat paint in homes built before 1978 as if it contained lead. See further information on lead if this applies to your home.

Most paints give off volatile organic compounds (VOCs)--chemicals that evaporate in the air--that could lead to IAQ problems. The ability of these chemicals to cause health effects varies greatly. As with any chemical, the likelihood of a reaction and the extent and type of health effect will depend on many factors. These factors include the amount of chemical in the indoor air, the length of time a person is exposed to the chemical, and a person's age, pre-existing medical conditions, and individual susceptibility. Eye and throat or lung irritation, headaches, dizziness, and vision problems are among the immediate symptoms that some people have experienced soon after exposure to some chemicals. In professional painters who are exposed to high levels of paint vapors for long periods of time, some chemicals in paints have damaged the nervous system, liver, and kidneys. Some chemicals cause cancer or reproductive and developmental effects in laboratory animals. Because of these concerns, susceptible people, such as young children and individuals with breathing problems, should avoid paint vapors. To avoid any health risks for themselves and their unborn babies, pregnant women should avoid undertaking painting projects and should limit their time in freshly painted rooms, especially when oil-based paints are being used.

Recommendations

1. Check that the painted surface is lead-free (or assume that any existing paint contains lead) before preparing a surface for repainting.

* Determine that the existing surface is lead-free OR assume surface contains lead-based paint.
* If paint is lead-based, use appropriate preparation and painting techniques.

2. Select an appropriate paint.

* Many water-based paints (even interior paints) have, until recently, used mercury as a fungicide. Any paint that contains mercury should not be used indoors. Evaluate any existing stock of paint and properly dispose of paints containing lead or mercury.
* With painting indoors, make sure you select paints that are for indoor use. Do not use exterior paints indoors.
* Evaluate new paint before you purchase it. There are two categories of interior paints, water-based and oil-based. Water-based paints are referred to as "latex" paints. The oil-based paints are referred to as "alkyd" paints. In general, water-based paints will emit fewer chemicals and lower levels of chemical vapors. Short-term exposure to solvents from alkyd paints can be significantly higher than from latex paints. Express your IAQ concerns to paint suppliers and use their technical personnel as a resource. Not all paint suppliers have information on pollutant emissions; consult other source (e.g., manufacturers) if your paint supplier cannot provide adequate information.

3. Always read and follow all the instructions and safety precautions on the label

* Do not assume you already know how to use the product. The hazards may be different from on product to another. some ingredients in individual products may also change over time. The label tells you what action you should take to reduce hazards and the first aid measures to use if there is a problem.

4. During interior painting, minimize exposing people to odors and contaminants.

* Try to schedule interior painting when the home is unoccupied, e.g., when people are at work or school, or on vacation. Under normal temperature and humidity, most emissions occur during drying, in the first few days after painting. You can also try to schedule painting for dry periods in the fall or spring, when windows are more easily left open for ventilation.
* Use exhaust fans to remove paint fumes from the building. Exhaust fans (such as a box fan, blowing from the room to the outdoors) should be used in the area being painted to remove fumes. Supply fans can be used in adjacent areas to keep fumes out. Operate fans and provide as much ventilation as possible continuously (24 hours/day, 7 days/week) from the beginning of the painting work until 2 or 3 days after painting has been completed.
* Block any heating or air-conditioning return openings--opening which send air back to the furnace or air-conditioner--in the rooms you are painting (if necessary turn off the regular home heating, cooling, or ventilation systems) to prevent circulating air from the work area to other areas of the home. If supply air is necessary for heating/cooling, make sure to provide adequate exhaust ventilation to avoid pressurizing the room and driving pollutants to other parts of the house. Do not block a cold air return with the furnace or air-conditioner running if it is the only return in the house.

5. Use Appropriate Storage and Disposal Practices for Paints, Solvents, and Clean-up Materials.

* Latex paint usually cleans up with soap and water. For alkyd paints, you will need to purchase specific products as listed on the label. Never use gasoline to clean paint brushes. Gasoline is extremely flammable. Read the label to find out if the paint cleaner is flammable. All flammable products should be used away from ignition sources such as water heaters, furnaces, electric motors, fans, etc.

6. Use Appropriate Storage and Disposal Practices for Paints, Solvents, and Clean-up Materials.

* Seal containers carefully after use.
* Buy only as much paint as you need to finish the job to avoid having to store or dispose of unused paint.
* When possible, keep paint containers in storage areas equipped with exhaust ventilation, but not near heating, ventilation, or air-conditioning equipment rooms.
* Use an appropriate waste disposal method to dispose of any paints containing lead or mercury.

7. Use and handle paint strippers properly.

* Paint strippers contain chemicals that loosen paint from surfaces. These chemicals can harm you if not used properly. Some paint stripping chemicals can irritate the skin and eyes, or cause headaches, drowsiness, nausea, dizziness, or loss of coordination. Some may cause cancer, reproductive problems, or damage of the liver, kidney, or brain. Others catch fire easily. Proper handling and use of paint strippers will reduce your exposure to these chemicals and lessen your health risk. From more information see What You Should Know About Using Paint Strippers, February 1995. (CPSC-F-747-F-95-002)

I'll add more links later. I have to go to work.