How "clean" does the dicor have to be when resealing ? and other questions ...

[mrffrank440]

Attempting some roofing maintenance. I was told that I must clean the existing dicor before applying new. I found that since the dicor is still soft, that cleaning it is almost impossible. I was told to use Pyroil (non-chlorinated) brake parts cleaner or acetone (water soaked rag) but the results were about the same. It looks like I am just moving the grime around. The "cleaned" spots is more from me removing the top layer than actually cleaning the surface.

As you can see in the bottom pic, there is a little "hole" in the dicor. I was able to smush the existing dicor to cover it.

Question #1 : How "Clean" must the exiting dicor have to be ? Must it look like "new"? How dirty is acceptable ?
Question #2 : What am I doing wrong, as I have seen on youtube how people are just wiping clean the dirt off their existing dicor ?
Question #3 : Should I remove all or most of the old, and just re-apply new?

[BadDogPSD]

Acrysol works really good for cleaning the areas that need resealed. If the sealant still has a strong bond, you can touch up by adding another layer of sealant. Dustin @ California RV Specialsts has some pretty good YouTube videos on how to evaluate, clean, & reseal the exterior of RV's.

[traveldawg]

If you are careful you can skim the top most part of the existing sealant with a multitool. You have to be careful not to tear the roof membrane. Someone else mentioned an aerosol spray. It's expensive and you use a lot tho to avoid what you said about just moving around the crud but it gets things clean; use lots of paper rags/towels.

[retired_engineer]

I clean the Dicor using Dawn dish soap and water. If the Dicor is still strongly adhered to the roof and fixture and only in need of a touch up or bubble repair I will final clean the Dicor area with a little mineral spirits on a rag and give it time to dry. I then put the new Dicor on top of the existing sealant.

[wudwork]

I was surprised how my heat gun softened the caulk up and I could finally get a plastic paint scraper underneath !

If you are careful you can skim the top most part of the existing sealant with a multitool. You have to be careful not to tear the roof membrane. Someone else mentioned an aerosol spray. It's expensive and you use a lot tho to avoid what you said about just moving around the crud but it gets things clean; use lots of paper rags/towels.

[mwdilday]

I read that Mineral spirits is not good for EPDM.

[Probe1957]

I read that Mineral spirits is not good for EPDM.

I was thinking I read the same thing.

[mrffrank440]

I was surprised how my heat gun softened the caulk up and I could finally get a plastic paint scraper underneath !

If the caulk was hard enough, then cleaning would be easier. But that gets back to my other question, that is if it is that soft, would just removing be better all, then re-caulking anew?

[Redapple63]

For cleaning I would start with just warm soapy water, then follow up with isopropyl alcohol. I would be ok adding a second layer. After that I would strip and recall. Too much build up could be deceiving in thinking there are no leaks.

My 2 cents.

Bill

[retired_engineer]

I read that Mineral spirits is not good for EPDM.

I don't use it on the roofing material. I only use it to clean up the Dicor surface before touching up the area with new Dicor. Most often the touch up is to fix a bubble caused by a screw. I remove the bubbled Dicor, clean up the Dicor around it and reseal. I've never had a problem or failure of the repair doing this.