waterproofing wood mounting rings

[perfecxionX 10+ year member]

When you put mounting rings on your car door do you guys apply polyurethane or anything like that to the wood to prevent it from absorbing water?

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[I Like Waffle]

no

 

[AlterEgo99 5,000+ posts]

They are typically located between the metal door and the interior door panel, which means if they are getting wet, you have bigger issues. //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[Rudy 10+ year member]

I do. After they're cut and drilled, I apply 3 or 4 soaking coats of polyester resin diluted 4:1 with acetone or styrene and the amount of hardener you'd use if the combined quantity of resin and solvent were all resin. Half hour between coats.

 

[audioholic 5,000+ posts]

Sometimes yes, if Im feeling anal, but usually no. Ive never had, or seen, a problem with a non-sealed wood adapter ring rotting due to moisture. But then, imo, most people on this forum get carried away with protecting their mdf from water. I once had a raw piece of mdf sitting in standing water for 3 days, my water heater broke and I didnt realize it, with my stack of mdf boards sitting right next to it. To listen to most people here, the wood would have swole up, deformed, and lost virtually all of its strength. Well, it didn't. No swelling, no deformation. Just a water stain left on the wood. I posted this info at the time, had about 50 people tell me I was wrong/stupid/crazy. The only way to shut them up was to post pics.

*shrug*

 

[Rudy 10+ year member]

It's possible that MDF varies regionally. The stuff I buy in Maryland is definitely negatively impacted by water. I guess the first lesson is not to stack MDF next to your water heater. When mine broke, several partial sheets spend less than 24 hours in less than inch of water for a day or so. The bottom 4 or 5 inches swelled and split. I've done a stupid amount of testing of MDF and water exposure. Submersion is obviously the worst case and you do have bigger problems if your mounting rings are under water.

The MDF I've used doesn't have to be underwater to be destroyed. I've even had problems cutting sheets outside when it started to rain - the areas hit by rain drops blistered. Occasional splattering and drying is a much more likely scenario in a car door. The MDF gets wet and swells slightly. It dries out and returns to almost its original shape except that the surface is more porous than it was before. The next time it gets wet it swells a little more and gets more porous. As this continues, the swelling meets resistance from the mechanical fasteners you used to mount the speaker to the MDF and the MDF to the door. It starts to pull apart. Humidity and living somewhere that it rains a lot probably makes a difference. If the OP faces those possibilities, throwing some water on some scraps will answer his question. If it dries exactly the same way it started, I wouldn't worry about. If it swells a little and feels rough, waterproofing makes sense.

 

[audioholic 5,000+ posts]

It's possible that MDF varies regionally. The stuff I buy in Maryland is definitely negatively impacted by water. I guess the first lesson is not to stack MDF next to your water heater. When mine broke, several partial sheets spend less than 24 hours in less than inch of water for a day or so. The bottom 4 or 5 inches swelled and split. I've done a stupid amount of testing of MDF and water exposure. Submersion is obviously the worst case and you do have bigger problems if your mounting rings are under water.
The MDF I've used doesn't have to be underwater to be destroyed. I've even had problems cutting sheets outside when it started to rain - the areas hit by rain drops blistered. Occasional splattering and drying is a much more likely scenario in a car door. The MDF gets wet and swells slightly. It dries out and returns to almost its original shape except that the surface is more porous than it was before. The next time it gets wet it swells a little more and gets more porous. As this continues, the swelling meets resistance from the mechanical fasteners you used to mount the speaker to the MDF and the MDF to the door. It starts to pull apart. Humidity and living somewhere that it rains a lot probably makes a difference. If the OP faces those possibilities, throwing some water on some scraps will answer his question. If it dries exactly the same way it started, I wouldn't worry about. If it swells a little and feels rough, waterproofing makes sense.

Maybe you are right, and its regional. Here's the pic of my 'experiment'.

 

[Jroo 10+ year member]

I have seen resin or the spray on bed liner you get a walmart.

 

[Rudy 10+ year member]

Maybe you are right, and its regional. Here's the pic of my 'experiment'.

Don't know about you but my new water heater is sitting in a pan with a PVC pipe running to a drain //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[ramos 5,000+ posts]

They are typically located between the metal door and the interior door panel, which means if they are getting wet, you have bigger issues. //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

Look at the bottoms of doors on 99.9% of the vehicles made today. They have drain holes down there for a reason. Water can and will work it's way into the door, even a brand new car. After removing multple baffles from assorted vehicles over the years, and seeing the effects moisture has on mdf in general. I switched to HDPE or Birch baffles. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[nateberrier 10+ year member]

i would do birch but if not just coat it with some resin and that usually sets you pretty well. maybe dilute it like said above

 

[ramos 5,000+ posts]

If you use the resin, just make sure you coat the baffle in resin AFTER all mounting holes are drlled in the baffle. If you don't the screw holes will still allow for water penetration. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif