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  • Mixing brands of uncured polyurethane

    I am refinishing a table top and I have 2 water based polyurethanes;

    Varathane waterbased professional clear finish

    http://www.canadiantire.ca/en/pdp/va...w.ds#store=389

    And Minwax water based oil modified Polyurethane

    https://www.canadiantire.ca/en/pdp/m...w.ds#store=604

    Both finishes are gloss and both cure to a beautiful Amber tone despite being water based. The only issue with the Varathane brand is sometimes random patches cure to a sort of dull, matte look, so I re-sand everything with 600 grit and apply another coat and then the same issue pops up somewhere else.

    I don't want to throw away the Varathane brand, so my plan is to mix roughly 50-50 of the two uncured finishes, (using all the Varathane brand I have left), apply several coats until this concoction is all used up, then put one or 2 final coats of the Minwax brand so there is no dull patches. (I always sand between every coat).

    Does anyone know of any potential problems with my plan or does it sound good to go?
    Starts
    07-08-2019
    Ends
    07-08-2019
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  • #2

    Re: Mixing brands of uncured polyurethane

    If they don't mix properly, you could find yourself with random sheen patches, or just a whole table covered in a rubbery, sticky goop that never dries

    how bad could it be?

    Comment


    • #3

      Re: Mixing brands of uncured polyurethane

      Originally posted by davezedlee View Post
      If they don't mix properly, you could find yourself with random sheen patches, or just a whole table covered in a rubbery, sticky goop that never dries

      how bad could it be?
      That is a good point, try it first on an area that will be easy to scrape/sand back off.

      Comment


      • #4

        Re: Mixing brands of uncured polyurethane

        By not using up the Varathane brand how much money are you actually losing, compared to a well finished job?
        How much is the extra work worth?
        John.
        If you learn from your mistakes, then I'm getting a fantastic education.

        Comment


        • #5

          Re: Mixing brands of uncured polyurethane

          That is a terrible idea.

          Nathan

          Comment


          • #6

            Re: Mixing brands of uncured polyurethane

            Thanks for the feedback guys. My plan to mix them uncured was to promote better adhesion between the initial coats and the final Minwax-only coat.
            Any thoughts on doing the first couple coats as Varathane only and then a couple more coats as Minwax only? (Sanding between coats)

            Comment

            • Thread Continues Below...

            • #7

              Re: Mixing brands of uncured polyurethane

              Obviously something is wrong with your Varathane...or were you not paying attention and you bought the version that says "Dries with ugly random flat spots at no extra charge."

              ....they discontinued that here in the east some years ago when it was found to be universally unpopular despite what the marketing department had said.

              Seriously though....there is something wrong with that product....so throw it out.

              Don't even think of mixing it, never mind that the two clear coats may be chemically incompatible (just because both say "waterbased"...does not mean they are "the same")......beer and wine are both water based....would you mix them?

              Anyhow, what makes you think that taking a can of good stuff and a can of bad stuff will make 2 cans of good stuff?
              It will not!

              To test this ...mix a glass of good fresh milk wth a glass of nasty old turned milk.....and drink some.
              Hmmmm....was it tasty and refreshing?
              Probably not, right?!
              .....you just successfully ruined both of them.

              Same with your urethanes...a right and wrong, when mixed together do NOT make a right!

              Ewwww...the horror!
              The logic does not prevail.

              I rest my case.....and yours!

              Bye for now.
              Good luck.
              Julian

              Comment


              • #8

                Re: Mixing brands of uncured polyurethane

                The idea was never that mixing the two would make "good stuff".
                The patches in the Varathane I believe are not due to being cloudy all the way through said coat, but due to spots where its surface has not cured smoothly; sort of like once I scuff the surface with ultrafine sandpaper it appears dull although there is nothing wrong with the coat other than its very surface not being smooth.
                As far as I am concerned, the Varathane brand is 'good stuff' except that spots on its very surface tend to come out not smooth for some reason.

                By making the final coat(s) Minwax I am confident there will be no patches, my only concern was the adhesion between coats of completely different brands, hence by mixing them I thought there was a lesser chance of adhesion problems between the initial coats and the final Minwax-only coat.

                Comment


                • #9

                  Re: Mixing brands of uncured polyurethane

                  There’s a good chance that it will not adhere properly.

                  Also a good chance that no one here has tried it.

                  Any reason you don’t want use only the minwax?

                  Nathan

                  Comment


                  • #10

                    Re: Mixing brands of uncured polyurethane

                    If your Varathane is either semi-gloss or satin, I'm betting that the bottom of the can has an uneven mixture of the flattening agents that are being randomly distributed as you put the coat on your work piece. If you are right down to the bottom of the can, it probably means you didn't mix the can properly for the top 3/4s and now you are stuck with a concentrated mixture that is hard to keep these bits suspended. I finished some cupboard doors once that turned out awful because it was the bottom of the can and I was trying to stretch the contents so I didn't have to go out and buy another can, but the final finish turned out milky and flat instead. Ended up having to sand it all off, fix the underlying stain colouring and redo with a new can of finish.

                    Now, as everyone above has already mentioned, mixing two brands probably won't work out the way you want because of the differing chemistries in the products - manufacturers have done some different things over the years with their products to meet the newer VOC regulations and there is no guarantee that the two will actually be able to dry and adhere properly when mixed.

                    John
                    nnieman likes this.
                    Shut up, wretched cricket of doom...

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                    • #11

                      Re: Mixing brands of uncured polyurethane

                      I'd be saving the Varathane for less critical projects like shop furniture, jigs, and shelves in the garage.
                      nnieman and iamtooler like this.

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                      • Thread Continues Below...

                      • #12

                        Re: Mixing brands of uncured polyurethane

                        I could say I like Varathane and hate Minwax. That would be the truth but it won't save your problem. Even the answers you got above don't convince you of the problem so why not mix some up and put it on a sample and see what you get? Sample, rhymes with Simple! I just thought that up,,,,,,,kinda good huh? LOL

                        BTW most people can't apply clear finishes properly. They brush it too much.
                        "Do it Right!"

                        Comment


                        • #13

                          Re: Mixing brands of uncured polyurethane

                          I'd chuck the Varathane. Uneven sheen often means it's old and partially cured (BTW, finish can cure even if it remains liquid and in the can). Either way, if it doesn't cure evenly on wood, something is wrong with it (it's not "good"...).

                          If you really want to recuperate, apply the Varathane, scuff sand, then apply the minwax. Varnish sticks to varnish especially when fresh. Then again, if the Varathane is already partially cured, it might not work as expected...which brings me back to chucking any finish that does not behave properly.
                          Last edited by Frank D.; 07-09-2019, 12:26 PM.
                          nnieman likes this.
                          Frank
                          SPCHT

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                          • #14

                            Re: Mixing brands of uncured polyurethane

                            Fine... You guys talked me out of it.
                            Applied my first coat this morning before work, Minwax only.
                            nnieman likes this.

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                            • #15

                              Re: Mixing brands of uncured polyurethane

                              If your objective is to economize and use up product instead of mixing your finish try using the Varathane as a base coat and the minwax as a top coat. You may need a bond coat between them like Target WB shellac or you may be able to get away with sanding. Since you got your brushes out anyway why not make up some sample boards? Do one with the mix and another as discrete coats .... maybe one with a bond coat and one just sanded. Let them cure then give them the torture test.

                              Personally I wouldn't do anything without doing a sample board first

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