Inlayind Formica

[Cooler]

It is done.  I started with a new sheet of plywood, less warped than the first.  Dry fit was perfect.  Glue-up not so.  Only thing I can figure is that the MDF swelled. The result is that the inlay is about 1/32 proud.  Not catastrophic And not very noticeable, but not what I wanted.  

Because the grain is matched across the counter, I can’t just make a new lid, so I will live with this for a while.

The shiny factory surfaces of MDF can take water based paint with no issue.  Once you sand a surface try to paint a machined edge the MDF will absorb water and "raise the grain" looking much like sandpaper when dry.  

If you inlet the MDF and used a water-based adhesive I would expect the MDF to swell.  An application of Sealcoat (or any dewaxed shellac) would seal the machined surface.  Shellac adheres to almost everything and almost any finish adheres well to shellac.  That having been said, I never tested adhesives over shellac, so a sample test would be in order.

It looks great in the photo.

An alternative would be to inlet 3/4" thick HDPE (high density polyethylene sheets).  If the shape is symmetrical you can flip it over to expose a fresh side.  Only use "natural" it is the only color that is considered food-safe. 

It would not be as attractive as your version however.

Side question (since you have a Dodge van).  I have long expected school minibuses to be made from those stand-up height vans, but they are still converting old commercial vans with an added height roof.  Any idea why?

[jteneyck]

I've never found MDF to swell when gluing it with TB type glues.  Only if you go nuts and soak it with water does it swell.  I think the issue here is more likely related to glue being trapped in the tight fitting recess such that the excess had no where to escape.  There is a lot of surface area and it would take a lot of clamping force to overcome that giant hydraulic piston you would create if the glue can't escape.  

John

[MsNomer]

Cooler, old-school mindset, I’d guess, 
  or maybe not:

Mercedes Sprinter vans are expensive to buy and operate.  Operating costs may become less of an issue with the new 2020 gas engine.  

RAM Promaster (like mine) is less expensive to buy and operate, but is not offered in a passenger version—cargo only.  Adding rear seats to meet safety standards is serious business and adds seriously to the cost.

Ford Transit is the best option for this use, and its use is increasing, but it can cost almost as much as a Sprinter. 

Also, Amazon just put a kink in the supply lines for all three with its massive purchases.

Regarding the shellac, I couldn’t do that because the edges were my glue surface.

Regarding trapped glue, there was none because I cut the crevice completely out.  However, the mistake may have been sizing the edge with thinned glue.  Probably shouldn’t have done that.

I have come to realize that I can redo the inlay without redoing the whole counter simply by making the inlay a hair bigger.  There’s nothing magic about its size.  I may try that when I have nothing better to do.

[Cooler]

I've never found MDF to swell when gluing it with TB type glues.  Only if you go nuts and soak it with water does it swell.  I think the issue here is more likely related to glue being trapped in the tight fitting recess such that the excess had no where to escape.  There is a lot of surface area and it would take a lot of clamping force to overcome that giant hydraulic piston you would create if the glue can't escape.  

John

If you apply latex paint to a machined edge of MDF it will raise the grain and make the surface look like sandpaper.  It probably amounts to 0.010" to 0.015" growth.  Paper is just 0.004" thick .

So if the MDF grew by just 0.008" - 0.012" it would move the formica about two or three paper thicknesses proud of the rest of the surface.  That would certainly be enough to feel if you ran your fingers across the surface. 

That is the amount of swelling I was referring to, and I do still believe that is a distinct possibility if she used a water based adhesive.  If she used a solvent based contact adhesive then, no.  There would be no swelling.

I always either use shellac or a shellac based primer on cut edges of MDF.  I usually use grain filler first for a perfectly smooth finish.

[jteneyck]

Cooler, old-school mindset, I’d guess, 
  or maybe not:

Mercedes Sprinter vans are expensive to buy and operate.  Operating costs may become less of an issue with the new 2020 gas engine.  

RAM Promaster (like mine) is less expensive to buy and operate, but is not offered in a passenger version—cargo only.  Adding rear seats to meet safety standards is serious business and adds seriously to the cost.

Ford Transit is the best option for this use, and its use is increasing, but it can cost almost as much as a Sprinter. 

Also, Amazon just put a kink in the supply lines for all three with its massive purchases.

Regarding the shellac, I couldn’t do that because the edges were my glue surface.

Regarding trapped glue, there was none because I cut the crevice completely out.  However, the mistake may have been sizing the edge with thinned glue.  Probably shouldn’t have done that.

I have come to realize that I can redo the inlay without redoing the whole counter simply by making the inlay a hair bigger.  There’s nothing magic about its size.  I may try that when I have nothing better to do.

If the panel was open on the bottom and you clamped the Formica flush with the countertop I don't see how the problem could have occurred.  

The only thing holding the panel in place is the glued edge?  

John

[MsNomer]

Yep, I used TB, and I think the real sin was sizing it.

[MsNomer]

The only thing holding the panel in place is the glued edge?  

John

That is correct, and no matter what I did, it simply would not go in, even though dry fit was fine. It now has a back on it, so there’s more holding it.