# Thinning Cover stain for exterior use.



## charleymcdowell (Mar 27, 2010)

Hi there! I know that the manufacturer probably would tell me not to do it but what I am wondering is how thinning cover-stain adversely affects it ability to do its job. I recently used my thinned down cover-stain to prime some french doors. I thinned it so I could apply a thin coat as well as decrease the dry time. Then I put two coats of KM Durapoxy eggshell. They came out nice enough but I am wondering if I should be worried about the longevity of this job. Thanks


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## SDpaint (Aug 5, 2009)

as long as it wasnt 50% thinner or something outragous I Think you should be fine. I thin down primers quite a bit myself and have never had a problem. when your using a stain blocking primer as an undercoater u dont need it to be full strenght, its super thick to block stains, but thats not needed in this case. You could also try some penetrol or xim in these situations, keeps the primer flowing for a bit longer before it locks up on you.


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## CApainter (Jun 29, 2007)

charleymcdowell said:


> Hi there! I know that the manufacturer probably would tell me not to do it but what I am wondering is how thinning cover-stain adversely affects it ability to do its job. I recently used my thinned down cover-stain to prime some french doors. I thinned it so I could apply a thin coat as well as decrease the dry time. Then I put two coats of KM Durapoxy eggshell. They came out nice enough but I am wondering if I should be worried about the longevity of this job. Thanks


Check out thinning recommendations here: http://www.zinsser.com/pdf/TDB/cover_oilbase.pdf

Too much thinning can result in less DFT, which could compromise the integrity of the primer.


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## CApainter (Jun 29, 2007)

I believe that's 12.5% thinner per gallon. (when using naphtha)


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## NCPaint1 (Aug 6, 2009)

Cover Stain isnt thin enough already?


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## charleymcdowell (Mar 27, 2010)

I don't know what the consistency is in Michigan but in SC coverstain is just a little thinner than elastomeric. Its kind of intense especially for an oil based primer. Some times it is inconsistent though I have had a couple of thin batches but mostly the former.


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## NCPaint1 (Aug 6, 2009)

charleymcdowell said:


> I don't know what the consistency is in Michigan but in SC coverstain is just a little thinner than elastomeric. Its kind of intense especially for an oil based primer. Some times it is inconsistent though I have had a couple of thin batches but mostly the former.


Makes sense. It could be a different formulation compliant with the state's VOC law. Here in Michigan its like water....just about. I stopped selling it about 6 months ago and replaced it with Isulx primer.


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## chrisn (Jul 15, 2007)

NCPaint1 said:


> Makes sense. It could be a different formulation compliant with the state's VOC law. Here in Michigan its like water....just about. I stopped selling it about 6 months ago and replaced it with Isulx primer.


 
It is like water here in MD also.


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## BC_Painter (Feb 14, 2010)

chrisn said:


> It is like water here in MD also.


Here in Western Canada too :thumbsup:


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## brushmonkey (Jan 4, 2010)

Coverstain gets pretty thick pretty fast in warmer regions. I went through alot of thinner last Aug doing exteriors just to keep it brushable. Evaporation is a biach.


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