Sample door for Client

[tjbnwi]

I use SW KA+ Surfacer on MDF edges without any prep to the edges. No issues with raising.

Tom

 

[JCLP]

Are you prepping the routed edges of the MDF in any way before you spray or does the primer do a good job of that?

I just sand the edges with 150 to get them smooth, spray the primer, snad with 320 grit or 240 and as long as you spray the recommended wet mils you will be good to go for paint.

Cheers,
JC

 

[JCLP]

My past experience with using a water based primer on raw mdf is that it will raise the “grain” on the surface of the mdf causing tiny bumps (almost like goosebumps). The edges will not seal despite the amount of coats I put unless I “seal” the edges first with something like joint compound or bondo. I was left with no choice but to use oil/solvent based primer like Zinsser coverstain. Can you share your experience and what you did to solve these issues? Thanks

Jeff

Yes. I have had that issue with other primers. Any primer will raise the "grain" to some extent but I found the Duralaq Undercoater did a great job especially when you sand it with 320 grit after 2 hours of drying. Make sure you spray on the recommended wet mils. Don't spray too thin.

Cheers,
JC

 

[toadjeep]

Thanks for the good info. @JCLP

 

[jaguar36]

What are you using to sand these? 

I've been looking at the Supermax brush/drum sander that they claim will do raised panel doors, curious how well that would work on profiles like that.

 

[JCLP]

What are you using to sand these? 

I've been looking at the Supermax brush/drum sander that they claim will do raised panel doors, curious how well that would work on profiles like that.

Before priming I use the DTS400 with 220 grit granat, as mdf is already sanded to 150. Once primed I use a sanding pad with 320 grit and hand sand the profiles by hand using foam backed paper, also 320 grit.
Cheers,
JC

 

[Alan G]

This has 2 coats of primer and sanded smooth as glass with 320 grit. Primer used is Duralaq Undercoater. Door built with MDF.

Are you using the Duralaq-WB or the Nitrocellulose Duralaq?
How dark of a color can they tint the top coat? You are getting at a local BM store?

So glad to see you got your spraying issues resolved. That door looks great! Nice work!

 

[tjbnwi]

What are you using to sand these? 

I've been looking at the Supermax brush/drum sander that they claim will do raised panel doors, curious how well that would work on profiles like that.

The SM does raise panels very well. There is a learning curve to get the brush height correct. What you think correct usually isn’t, the brush expands slightly when it spins up.

1200 CFM dust collection or higher is a must.

Tom

 

[JYip]

My past experience with using a water based primer on raw mdf is that it will raise the “grain” on the surface of the mdf causing tiny bumps (almost like goosebumps). The edges will not seal despite the amount of coats I put unless I “seal” the edges first with something like joint compound or bondo. I was left with no choice but to use oil/solvent based primer like Zinsser coverstain. Can you share your experience and what you did to solve these issues? Thanks

Jeff

Yes. I have had that issue with other primers. Any primer will raise the "grain" to some extent but I found the Duralaq Undercoater did a great job especially when you sand it with 320 grit after 2 hours of drying. Make sure you spray on the recommended wet mils. Don't spray too thin.

Cheers,
JC

So the Duralaq does raise the grain then? Sounds like you just sprayed on a thicker coat to deal with this issue? In my experience, you can feel the raised grain "bumps" with your fingernail so I'm not sure if thicker coats can cover them up but maybe I'll give it a try. Thanks

Jeff