11:43AM | 03/11/04
Member Since: 03/10/04
2 lifetime posts
Are siding was replace a year ago with T1-11 siding.

The painter used Zinser Bin Shellac to prime the surface. This primer is not recommended for T1-11.

Now all the paint is peeling and some panels have delaminated.

Do you think this siding can be saved or has too much damaged occured? Since it never was really weather proffed with a good primer.


05:58PM | 03/11/04
Member Since: 01/28/03
693 lifetime posts
It is my opinion that the t1-11 should probably be replaced, properly primed and painted or stained.

The reason is that any attempt to seal over the existing shellac won't work if the shellac rpimer is going to continue to peel right off, and there really isn't an economical means of removing the primer and paint that's on there now short of having it professionally 'burned' off.


03:31PM | 03/12/04
Member Since: 07/28/02
1356 lifetime posts
Once T1-111 starts to delaminate it is time to replace it as it will just keep on doing it. You have found out first hand why you don't prime large exterior areas with shellac. You prime T1-111 with an exterior acrylic primer and finish with acrylic house paint in a flat or satin finish. You also don't use oil based products on T1-111 as it will cause delaminating when it attacks the glues in the plywood.

If you decide to spray the paint on the T1-111 as I am sure someone will suggest, you will need to back roll it to get the grooves coated well.


07:25PM | 03/13/04
Member Since: 01/28/03
693 lifetime posts
5slb6 said:

"You also don't use oil based products on T1-111 as it will cause delaminating when it attacks the glues in the plywood."

homebild replies:

REALLY? 5slb6?

I never heard that before.

I would have honestly suggested that any thinned oil based or shellac primer or paint would work wonderously on T1-11 as a 1st, 2nd, or 3rd base coat.

Can you provide some links or ecidence to back your claims?

I am not trying to be argumentative....But I AM questioning your allegations and would like to examine the evidence for myself.

Best Regards and open to your instruction....



03:35PM | 03/15/04
Member Since: 07/28/02
1356 lifetime posts
For information on the use of shellac outside go to and I will see if I can find anything in written form on the use of oil based paints on plywood.


04:10PM | 03/15/04
Member Since: 07/28/02
1356 lifetime posts
Foe the life of me I don't know were people get the idea that if you thin down finish paint it turns into a primer, if you have noticed primers are not thin as water. Primers are designed to seal and bond to the surface and give something for the finish paint to stick to.

Look at these web sites for a recomendation on painting plywood.


11:51AM | 03/16/04
Member Since: 01/28/03
693 lifetime posts
No one (not me anyway) is suggesting that thinning finish paints turns them into primers.

However, what I AM suggesting is that by thinning certain exterior paints they can be made to act more or less like "STAINS" which allows them to penetrate the wood to be finished rather than simply dry on top of it as do primers.

This technique is especially common when finishing wood floors, both interiorly and exteriorly.

This is a commonly accepted technique and in fact is taught by manufacturers as an acceptable technique under limited circumstances.


03:46PM | 03/16/04
Member Since: 07/28/02
1356 lifetime posts
If you thin down paint like a stain it will not hold up on an exterior siding as you don't have the properties that the paint was designed to have. If you want stain buy stain as they are designed to hold up on an exterior siding. There are 2 types of stains for exterior siding and they are soild which masks the grain but allows the texture to show through and semi-transparent which allows the grain to show through.

It is fine to thin a product down to make a stain as long as the manufactuer designed it that way, but I doubt you have a paint company tell you to thin down a regular house paint to make a stain out of it.


05:40PM | 03/18/04
Member Since: 01/28/03
693 lifetime posts
Perhaps I did not make myself clear, but the paint is applied in successively 'thicker' coats.

The process is to apply the first coat with a 3:1 thinner to paint ratio.

The next coat will be a 2:1 ratio thinner to paint ratio.

Following coat would be 1:1 thinner to paint.

Successive coats at full 0:1 paint.

The major advantage of the process is that the initial thin coats are much more able to penetrate the wood and create a better bonding subsurface than any primer.

The major disadvantage is that it does require multiple coats.

In certain applications it is far superior than any primer-paint application and far superior than stain alone.

Pittsburgh, DeVoe, Coronado among other manufacturers all recommend the technique under certain applications.


01:29PM | 03/20/04
Member Since: 07/28/02
1356 lifetime posts
I have never heard of a paint manufactuer reccomending to thin paint 3to1 make a primer. If that was the case why do we have primer, as it would be cheaper for us just to have finish paint and plenty of paint thinner.

The difference between a primer and a finish paint is that a primer has more resin and less pigment for the added adhesion and sealing properties that you need from a primer and that is why primers don't cover as well as finish paints.

The way you are talking about painting a surface there will not be hardly any film build and it will not hold up as long as paint applied like it was designed to be.

Primer is for priming and finish paint is for finishing. I have been in the paint business for 28 years and I have delt with people that have the same view on painting as you do and all it does is make the paint companies look bad when the paint job fails. So stop trying to be a chemist.
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