Re: Best methods for finishing MDF
This thread was mainly about finding a way to stop the seams from telegraphing on a b u t t joint MDF box using a method that inexperienced builders could do inexpensively. It was discussed that the ultimate way would be West System Marine epoxy. The down side is the price. I think when I looked into it it would be over $100 in materials which is high for a budget build. Also takes experience to use properly. I should also add I have become sensitized to epoxy from using it without proper protection. After all my testing the only method I found that worked well was the trench method filled with finishing putty or just plain body putty. Putting a thin layer over the entire box also helped on the transition from the putty to the MDF. I had also came to the conclusion the less moisture you add to the MDF the better. Thinning products down to soak in only seemed to break down the binding material in the MDF and allows it to expand. It also seems the more it expands the more unstable it becomes. Probably why the epoxy works so well. It sets up on the surface, seals out moisture and will bridge any movement in the seam. Here is a link to the boxes I built to test the trenched seams. I really abused these boxes by heating them up with a heat lamp and catching one on fire,painting, clear coating then putting self leveling resin on them. Then stripping them and repainting and clear coating. As of today still no seams. Interestingly the box I caught on fire does seem to be showing signs of movement in the box . Not sure why other then too much heat destabilized the MDF. I'll have to update how each sample I made is doing when I get some time. Post #36 and #115 show some of the samples I did and post #172 shows my test box updates from almost a year ago.
Dave
This thread was mainly about finding a way to stop the seams from telegraphing on a b u t t joint MDF box using a method that inexperienced builders could do inexpensively. It was discussed that the ultimate way would be West System Marine epoxy. The down side is the price. I think when I looked into it it would be over $100 in materials which is high for a budget build. Also takes experience to use properly. I should also add I have become sensitized to epoxy from using it without proper protection. After all my testing the only method I found that worked well was the trench method filled with finishing putty or just plain body putty. Putting a thin layer over the entire box also helped on the transition from the putty to the MDF. I had also came to the conclusion the less moisture you add to the MDF the better. Thinning products down to soak in only seemed to break down the binding material in the MDF and allows it to expand. It also seems the more it expands the more unstable it becomes. Probably why the epoxy works so well. It sets up on the surface, seals out moisture and will bridge any movement in the seam. Here is a link to the boxes I built to test the trenched seams. I really abused these boxes by heating them up with a heat lamp and catching one on fire,painting, clear coating then putting self leveling resin on them. Then stripping them and repainting and clear coating. As of today still no seams. Interestingly the box I caught on fire does seem to be showing signs of movement in the box . Not sure why other then too much heat destabilized the MDF. I'll have to update how each sample I made is doing when I get some time. Post #36 and #115 show some of the samples I did and post #172 shows my test box updates from almost a year ago.
Dave
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