[NoahH]

I am getting ready to to take my baffles to the auto body shop Monday for painting, and a conversation with a friend has made me question if I need to pre-treat the wood in some form. The auto shop is going to prime and paint, but it sounds like I may need to put a sealer on the MDF first to keep it from absorbing the solvents in the primer?

Any advice?

[daven3871]

Top choice  you can look into finding it spray application only.
Chemcraft product 522-1410 MDF primer.

[NoahH]

Top choice  you can look into finding it spray application only.
Chemcraft product 522-1410 MDF primer.

How bad is cleaning the sprayer afterwards? Reason I ask is that for anything with a sprayer application, I think I should try to get the auto shop to do it since I am trying to avoid a whole sprayer setup, but asking them to do it on something hard to clean out is tricky.

Thanks for the advice too!

[JCarney]

The primer will be the sealer. Any clear sealer you apply will also have solvents in it. The solvents in the primer and/or sealer help with the penetration and sealing of the mdf. The main difference between the two is the solids. Primer has more solids and gives a better surface for paint finishing. Auto paint is very high in solvents, and applying something before hand should be discussed with the shop to ensure you use something compatible with their products. Take them the raw baffles and let them do their thing is the best advice I think.

Good Luck,
JCarney

[daven3871]

How bad is cleaning the sprayer afterwards? Reason I ask is that for anything with a sprayer application, I think I should try to get the auto shop to do it since I am trying to avoid a whole sprayer setup, but asking them to do it on something hard to clean out is tricky.

Thanks for the advice too!

Not sure if the shop will have ever used MDF as a substrate or not if not they may be in for a eye opening experience or disaster I’m giving the recommendation based on experience and same I give every cabinet maker when doing painted job. I do not know what topcoat or system they may use but the primer be ideal for any 2k system or used as undercoat for whatever sealer they would apply prior to color. As far as cleaning it’s no different than any other 2k primer clean up.

[nlitworld]

Most body shops willing to paint speakers know there are a few options to painting MDF. First is using a glazing putty (thin body filler) on all the seams and sanding that smooth. Next is using a polyester primer (sprayable body filler) to prime first, then using urethane primer or sealer before paint or just using straight urethane primer in 2 applications of ~4 coats each with block sanding in between. Either way, it is a lot of work which is why most body shops will charge somewhere between $500-$1,000 to paint a set of speakers. Super custom work or really big set would go even above that.

For what you are asking I wouldn't be worried about it one bit. Just have a conversation about making sure they are super flat and smooth and they should know how to handle it.

If you have any questions along the way, let me know and I'll walk you through the whole thing. My 8-5 gig is selling automotive paint so I can walk you through the whole process if there's any questions.
-Lloyd

[daven3871]

Most body shops willing to paint speakers know there are a few options to painting MDF. First is using a glazing putty (thin body filler) on all the seams and sanding that smooth. Next is using a polyester primer (sprayable body filler) to prime first, then using urethane primer or sealer before paint or just using straight urethane primer in 2 applications of ~4 coats each with block sanding in between. Either way, it is a lot of work which is why most body shops will charge somewhere between $500-$1,000 to paint a set of speakers. Super custom work or really big set would go even above that.

For what you are asking I wouldn't be worried about it one bit. Just have a conversation about making sure they are super flat and smooth and they should know how to handle it.

If you have any questions along the way, let me know and I'll walk you through the whole thing. My 8-5 gig is selling automotive paint so I can walk you through the whole process if there's any questions.
-Lloyd

The material suggested is specific to the issue with MDF can you spec a automotive primer with tec sheet that addresses MDF I’ll bet not.
https://www.richelieu.com/documents/docsGr/116/470/2/1164702/1270403.pdf

[nlitworld]

The material suggested is specific to the issue with MDF can you spec a automotive primer with tec sheet that addresses MDF I’ll bet not.
https://www.richelieu.com/documents/docsGr/116/470/2/1164702/1270403.pdf

Automotive primer is perfectly suitable on wood and mdf and any other similar substrate. But due to it being very porous it will absorb a ton thus the multiple applications. The plus side though is that there is no chemical incompatibility with any other products. Also, if they were using the glazing putty for the seams, they certainly could just skim coat the entire outside and sand smooth to eliminate the first priming step all together. But specifically I did call out polyester primer as a valid option and Evercoat Slick Sand specifically mentions suitable on wood surfaces.

https://evercoat.com/images/ePIM/original/TDS_100709_SLICK-SAND-3.2021-US-ENG.pdf

Point being, adhesion and holdout with wood is a cake walk. Adhesion to fiberglass, steel and aluminum designed for daily driving in all conditions is a lot more difficult. Even the basic low grade automotive products are a huge step up in quality from woodworking materials.

[daven3871]

Automotive primer is perfectly suitable on wood and mdf and any other similar substrate. But due to it being very porous it will absorb a ton thus the multiple applications. The plus side though is that there is no chemical incompatibility with any other products. Also, if they were using the glazing putty for the seams, they certainly could just skim coat the entire outside and sand smooth to eliminate the first priming step all together. But specifically I did call out polyester primer as a valid option and Evercoat Slick Sand specifically mentions suitable on wood surfaces.

https://evercoat.com/images/ePIM/original/TDS_100709_SLICK-SAND-3.2021-US-ENG.pdf

Point being, adhesion and holdout with wood is a cake walk. Adhesion to fiberglass, steel and aluminum designed for daily driving in all conditions is a lot more difficult. Even the basic low grade automotive products are a huge step up in quality from woodworking materials.

I use to think and seen people go through tireless steps until you used a proper product designed for the specific substrate

[WGH]

Let the paint shop do the sealing/priming. Bondo works well for fixing small or large blemishes.

We use Sherwin Williams Sher-Wood Kemvar Conversion Varnish, a high solids catalyzed wood finishing system offering a superior quality for furniture, cabinets and interior wood product. Kemvar is a catalyzed colored varnish so you need a spray booth with an exhaust fan and a lot of time. Finishing will take as long or longer than construction.

https://industrial.sherwin-williams.com/na/us/en/industrial-wood/catalog/product/products-by-industry.11543394/sher-wood-kemvar-plus-conversion-varnish.9198022.html

Kemvar Sealer—catalyze and reduce Varnish as a sealer. Spray a full wet coat. Air dry 30 minutes, sand, repeat, sand, repeat.

Old 2017 prices:
Kemvar is only available through a Sherwin Williams Commercial Dealer.
1 gallon Kemvar     $90.00
Catalyst                 $26.69
Lacquer thinner     $13.73
Sealer                    $37.01
Total                     $167.43

Colored primer on maple wood legs and combo-core plywood which has an MDF top and bottom and plywood center for a super smooth, flat surface.


Finished table and stools with color coat. The color is rubbed through to show red in places for a distressed look.
A clear coat of Kemvar Conversion Varnish added another layer of protection.

The black table top and shelf is flawless and looks like polished black granite but is lighter and cheaper. If we used granite I thought a 500 lb coffee table would be a little too much.

[NoahH]

Thank you all for some great advice. Much appreciated.

And WGH - that is some gorgeous work!

[mkane]

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