Sherwin Williams DURATION PAINT and Mildew Problems
by Joe Mehaffey
Updated 4/19/2011

I painted a home in about 1998 with Duration paint and have been extremely pleased.  As of 2005, there is no evidence of mildew or molds on the paint surfaces anywhere.  In 2000 and 2001 I built a guest house, pool house and a 20x40ft shade pergola within 100 feet of the main house.  Within 2 years, the shady sides of all three of these new structures were covered with black mold on the surface of the Duration paint.  In 2004, the local paint store told me to pressure wash it with bleach and then they gave me some spray on mildew treatment that was supposed to fix the problem.  In the summer of 2005, the mold was back as bad as before on all the treated surfaces.

I spoke with Sherwin Williams "Help Line" who basically told me "Mold happens, live with it", and "No paint is immune to mold".  This is a nice pitch, but it fails to explain what I believed MUST have been a change in formulation of Duration between 1998 and 2001.  Further research disclosed that the EPA caused paint manufacturers to change their formulations in that time interval and the new formulation (of Duration at least) are now much more prone to mildew growth.  

It does not help to have paint guaranteed to last 25 years if it turns black with mildew in a couple of years!  Sherwin Williams offered to provide free paint to renew the problem buildings but only offered $200 of the $2200 labor cost.  This on a paint job on three structures less than 2 years old!  This strikes me as a very poor warranty response on a manufacturer's premium product.

I went ahead and took the replacement Duration paint and added TWO tubes of M1 mildewcide to the gallon of paint.  Hopefully, this will give the Duration paint what it takes to go for a longer duration than 2 years!  Sherwin Williams now tells me that they are aware of the problem and that the mildew problem has shown up only in the Southeast USA and in coastal areas elsewhere.  They also say they are working on designing an improved formulation of Duration paint that will not have this problem.  

Meanwhile, I recommend you consider adding a couple of tubes of M1 mildew preventer to each gallon of Duration paint toward preventing early discoloration of Duration by Mildew if you happen to be in a mildew prone area of the country.

 If anyone knows of a high quality and long lasting house paint that also has superior mildew resistance,  please let me know.

The White Duration Paint installed in 2005 has gone now for 18 months with no signs of mildew.  I tried the same paint  with two tubes of M1 mildew preventer on some 10year old unpainted "treated lumber" fence in 2004.  The mildew did not appear by now, but the paint has not stuck to the fence and I am now having it sandblasted, pressure washed, scraped and repainted with conventional paint.  Personally, I will not be using any more Duration Paint..  Too many problems.

My son painted his home in 2003 with some Grey Duration paint.  By 2005, the grey paint that was exposed to the sun had become "seriously pink".  The part in the shade had not changed color.  Sherwin Williams gave him Duration paint (grey) to repaint the affected areas in the Spring of 2005 along with paying half the cost of reapplication.  Those areas are again showing a "pink tint" after about 18 months.  Seems like Sherwin Williams has some serious re-formulation to do on their Duration Paint.

I have renamed the  SW Duration paint product SHORT DURATION paint.  The Duration Paint I used BEFORE  year 2000 has performed well indeed and is still in excellent condition.  But all of the Duration paint I have used since the formula change  has performed poorly in one way or another.  This year, I am repainting (for the third time in 8 years) the 25x40ft louvered pergola at the rear of my home as well as several smaller project previously coated with Duration.  The duration paint on the pergola has failed both by peeling off (on the top of the pergola exposed to the direct sunlight) and it had mildew on the areas NOT exposed to the sun.  All in all, a disgraceful failure in 4 years  for what is supposed to be a Sherwin Williams premium paint product.

I started using a Benjamin Moore "best grade" product in 2005 and (so far) it is holding up fine.  I am repainting the pergola with an Olympic Oil based paint that is showing promise on some outbuilding painting done in 2006.  Both of these products (so far) are not showing any evidence of mildew or other problems, but it is really too soon to give them a blessing.  I also painted some trim on my own home with Sealoflex Premium White in late 2006 but it is too soon to report.

The "before 2000" Duration paint has continued to perform well.  All "younger" Duration paint has been repainted because of paint film failure.  The Olympic Brand paint has performed rather well in ordinary trim paiting, but any painted onto plywood failed prematurely due to its non-elastic failure when the grain in the plywood separated slightly.  Overall  Olympic is a pretty good house paint.

The Benjamin Moore paint has helf up well in ordinary trim painting but has not performed to excellence in mildew prone areas.  However, it is better than Duration.

I painted much of the trim on my own home using Sealoflex "Sealcoat Elastic" Premium White in 2006.  Last year, I painted a new stucco area on another home with the Sealcoat Elastic primer (it is thin) and then with the Sealcoat Elastic Premium) which has a much heavier paint body.  Note that fresh stucco soaks up a good bit of primer as discussed in the links below.  All this paint has, so far, exceeded my expectations.  The older paint has proved extremely resistant to mildew and has held up well in fully exposed areas on trim.  It was used on some trim with small splits in the wood fiber and it covered these well and its VERY elastic and rubbery nature has allowed it to remain sealed even though some of the thin cracks have expanded slightly.  I am now using this paint on both wood and stucco (with the proper primers) and on fiberglass blinds and posts.  This paint is available only through industrial paint suppliers and only in 5 gallon pails.  However the price is competitive with the better grade paints from Sherwin Williams, Benjamin Moore and others.  At present, this is the paint that I would recommend using as a house paint.  NOTE:  I have only used the SEALCOAT ELASTIC PREMIUM paint and its primers.  I have no experience with other Sealoflex products.   I will report further on Sealoflex  Elastic paint in future updates.  See:

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