Adhesion issues revisited, question for y'all

[IPT]

Hey guys I have a question. A while ago I was posting about some adhesion issues I had witha project. it was MDF sealed with water based poly and then covered with hi build primer, sanded smooth with 400 or 600. I think put Autoair sealer on it and began the project.

I had some adhesion issues. In retrospect and after just reading something about 2K primers they are apparently quite absorbent. Should i have used an epoxy type sealer over it, or mabe too begin with? I'm wondering now if using the waterbased paint over a hi build primer softened the primer base leading to my adhesion issues?

The goal is to seal MDF panels for painting. My current plan would be seal with poly to seal the wood. I need to maybe do some fillers to smooth it out, but then what? Could I just use Autobourne directly over filler (filled dings) with a poly base?

 

[Nada]

I like a pva primer on bare surface wood. I can tell you pva primer then gesso on hardboard will not lift.
You can adhere autobourne direct, however pva primer is many times cheaper.

 

[Nada]

Hey guys I have a question. A while ago I was posting about some adhesion issues I had witha project. it was MDF sealed with water based poly and then covered with hi build primer, sanded smooth with 400 or 600. I think put Autoair sealer on it and began the project.

I had some adhesion issues. In retrospect and after just reading something about 2K primers they are apparently quite absorbent. Should i have used an epoxy type sealer over it, or mabe too begin with? I'm wondering now if using the waterbased paint over a hi build primer softened the primer base leading to my adhesion issues?

The goal is to seal MDF panels for painting. My current plan would be seal with poly to seal the wood. I need to maybe do some fillers to smooth it out, but then what? Could I just use Autobourne directly over filler (filled dings) with a poly base?

What are you using these for indoor art? Outdoor? Just show off panels?

 

[IPT]

Indoor. Last project was the drawer front and doors on a homemade cabinet. Next is going to be a table/trunk top.

This was the last project.

 

[IPT]

I like a pva primer on bare surface wood. I can tell you pva primer then gesso on hardboard will not lift.
You can adhere autobourne direct, however pva primer is many times cheaper.

I understand that Autobourne can go straight onto wood, but I'd think MDF would soak it up like a sponge. Hence the reason for wanting to use at least a poly to "seal" it. I'm thinking I could use a Poly and let it cure. Then I do some ding repair with a filler and then Autobourne right over that (the Poly and a few specs of filler). That should work, yeah?

I'll need to look into the PVA primer.

Today i read about the filler primer being very absorbent and it just got me wondering about my failures on the above project. It could have been the hi build primer soaked up the Autoair sealer a lot + I might not have let the sealer cure enough and built up my layers to quick. Now I have Autobourne and enough experience (AKA failures) to make sure it is cured before laying a new coat .

 

[splasha]

You could make up a batch of PVA Glue mixed with water, and paint it / spray it onto the MDF. [Filter it thoroughly first!]
If you're impatient you then set it off with a heat gun on low setting.
After this, you coat it with whatever primer you wish and then, when it dries - give it a sand and you're good to go.
Just be sure you have totally sealed the surface, because MDF will suck up so much stuff first off, it'll amaze you!
Don't be surprised if you have to go back over the first layer because there were some tiny spots uncovered.
I will usually put at least 2 coats, and then, if I'm still not satisfied, I'll go for another 1 to be certain.
It's the flatness of these coats that is critical to the finish, especially if it's going to be a display piece that gets cleared at the finish.
Once you have a build up happening, take the time to smooth off the surface BEFORE laying down your artwork.
Should all be good from there, I reckon.
Splasha

 

[IPT]

Thanks Splasha. I did a test piece with water based poly. Sprayed one, painted the other. Brush strokes in the painted one and need to spray much thicker on the other one (will need the mini gun, the AB isn't going to cut it). I sanded the brush strokes mostly down hoping the clear would cover it. The clear did cover it, but didn't mask it . No worries though, it was just a test piece.

I think if I spray on the poly thick enough that will work and I won't need primer. I think the Autoborne will adhere to the scuffed Poly. It did on the test piece so far. That's been cleared too without issue. I don't for see issues with taping but we will see .

 

[Nada]

Indoor. Last project was the drawer front and doors on a homemade cabinet. Next is going to be a table/trunk top.

This was the last project.

I remember that piece. Seeing it again may inspire me to do my first American flag.

 

[IPT]

I remember that piece. Seeing it again may inspire me to do my first American flag.

You should! It was fun and not tedious like some of the other stuff we do that requires a lot of scratching and fine details .

 

[Nada]

You should! It was fun and not tedious like some of the other stuff we do that requires a lot of scratching and fine details .

The only thing i have scratched lately is my butt!

 

[Maple Art]

I was told this process at the last class that I hosted the class project was on hardboard/MDF

hardboard/mdf prep:
Sand lightly removing any imperfections
primed with Tremclad primer
based with Tremclad black
cleared with 2k clear
scuff
degrease and paint...


worked really well no paint lifting problems and they were masking over fresh paint.

Donna

 

[IPT]

Thanks Maple. Honestly, and I could be wrong, I think the 2K clear is the key. The autobody guy said the issue with the wood is its ability to suck stuff up. Once it's sealed you're good to go. his suggestion was to seal with something water based because he though the solvent could get absorbed deep into the wood. that would either degrade the wood, or try and come out later once it's sealed from above and cause issues. Seems to me the 2K will form a reallty solid base to tape on. That's the step I skipped the first time.

I think sealing with sealing with water based poly that is designed for wood is the optimal choice. Though clearly the Tremclad worked too . Once it's sealed probably doesn't matter what you spray over it . So my plan is, or should I say I already did a test piece with poly, then Autobourne, then 2K clear. Haven't taped on it yet but I wet sanded it and had zero issues so far. I'll keep you updated. Thanks for sharing what you learned!

 

[twood]

When I use the hardboard lately, I lightly scuff, use rustoleum primer, then base with the rustoleum base. I dont clear, just skuff the base and paint. I did this sign using Oracle 651 and had no peel up of the base. There was alot of mask on this, and it was scary when I removed it because this stuff is pretty sticky, but had no issue at all.

It was based in black, so the mask is everything you see black....
I love using hardboard and am going to get another 4x8 sheet. It gives me 12 16x20 pieces for 40 dollars
Cheers

 

[GMuxx]

My original plan for learning to airbrush was to use it for designs on shop and pub chalkboards - up until now I have painted mdf with smooth black masonry paint and done my designs on top with liquid chalk pens and acrylic paints with a hairy brush. They don't have to be super smooth and very detailed and will likely be temporary. If I do use an airbrush with acrylic paints, do I have to spray something over the design afterwards to waterproof it?

 

[RebelAir]

Id be more worried about the 2k chemically breaking down the glues in the MDF which i dunno if its still is but you could be creating some cool chemicals as they used to use formaldehyde in the stuff, which is why you used to have to protect yourself well when cutting the stuff. But painted on MDF for years and all I used to use was my white airbrush paint, base it a few times and with enough layers it soon sealed it fine Then a light sanding and start painting..Have also used various other waterbased house paints etc to do the same sealing when I felt I was using paint that was too expensive for sealing LOL..Although I did also once or twice use some Sonja Jos sealer from bunnings and that seemd to work fine also..I assume you may want to stick with uro's maybe, if not just do the same without the fillers and primers as I never found any adhesion issues at all just sealing with your basic base coat...But as to how the 2k will react deeper in the mdf I couldnt honestly say...

 

[Nada]

My original plan for learning to airbrush was to use it for designs on shop and pub chalkboards - up until now I have painted mdf with smooth black masonry paint and done my designs on top with liquid chalk pens and acrylic paints with a hairy brush. They don't have to be super smooth and very detailed and will likely be temporary. If I do use an airbrush with acrylic paints, do I have to spray something over the design afterwards to waterproof it?

Clearcoating is nice to seal in and protect your art. However depending on paint used may not be necessary.
For instance wicked paint will hold up outdoors with no clear.
And certainly longer than chalk paints.
If not being exposed to rain regularly and as you say temporary you should be fine.
Every quality airbrush paint is somewhat lightfast. Direct uv exposure for 6 months has shown no fading on any art i have done using
Golden high flows
Com art
Wicked
Createx illustration
Createx airbrush colors

 

[IPT]

thanks for all the input. Yeah the idea was to use something cheep, like Poly to seal the wood (since MDF will often absorb a lot). My idea behind the 2K was to create a sort of shell on top of that providing a very solid base to tape on. Looks like as usual with custom painting there are lots of ways to do things! I guess my adhesion issues the first time just left me wondering how to do it better. In hindsight I think I probably just pounded on the Sealer too quickly leading to my adhesion issues.

I might just try to Autoborne directly to the MDF and see how it goes . Sure would be nice to skip the extra steps and not have to spray the nasty 2k clear twice. Everything I do currently is water based with the exception of the clear coats . I would like to try the water drop thing though so having clear over the base would be a plus. So many choices .

 

[GMuxx]

Clearcoating is nice to seal in and protect your art. However depending on paint used may not be necessary.
For instance wicked paint will hold up outdoors with no clear.
And certainly longer than chalk paints.
If not being exposed to rain regularly and as you say temporary you should be fine.
Every quality airbrush paint is somewhat lightfast. Direct uv exposure for 6 months has shown no fading on any art i have done using
Golden high flows
Com art
Wicked
Createx illustration
Createx airbrush colors

I will be using wicked detail and createx airbrush colors. Thanks for that.

Sorry if I hijacked your thread IPT

 

[Kelan]

I need clarification on where your adhesion issues are stemming from as you have multiple layers you are dealing with. Poly, primer, sealer, and paint. I think this can help us narrow down your problem.

 

[RebelAir]

How bout just screwing a sheet of thin steel to it, then 2k away Washing machine panel would mount well on MDF..Ultimate seal