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Repairs/respray MDF cabinet?

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Mike.S

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I'm just completing this MDF cabinet:



and am unsure how best to approach the repairs needed before/after spraying (mid-sheen white paint finish of some sort). By repairs I mean correcting my inaccurate cutting e.g.:



The unit can be disassembled, which I propose to do in order to make it easier to spray before reassembling (permanently) in situ. I can them fill/caulk the gaps but my concern is that any touch-up re-spray to cover such repairs will be too visible. In other words, what I'm asking is whether it is possible to blend in sprayed paint over a newly sprayed (but dried) surface?

If you can't already tell I'm completely new to spraying (other than respraying the replacement wings on my MK1 Escort 30 years ago!). I'll be using a Fuji HVLP spray system. Current thoughts are to spray 2-3 coats of Shellac sanding sealer followed by 1-2 coats of primer and 2 coats of paint finish. Will this be durable enough or should some sort of final clear coat finish be applied?

Guidance would be greatly appreciated.

Mike
 

cornucopia

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its best practice to prime/seal the mdf before you try any repairs- that way the filler or caulk won’t be absorbed by the mdf and cause any staining.
I was trained how to spray but never did allot outside of the classroom- but I think you'd be better of doing 1 coat sealer/primer 2 top coats- if I was doing it by brush I’d only do 1 coat zinnser BIN 2/3 top coats so I think your 5/6 coats is making hard work for yourself.
 

Mike.S

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Thanks cornucopia

Likely that I'm over engineering things (a trait I'm trying to moderate). My thinking was that the sealer would act to minimise moisture absorption (an article I read based on US research suggests Shellac is best, though 6 coats were specified!) and minimise trouble with the usually problematic MDF edges. But perhaps 1 decent coat of primer, like Zinnser BIN, might suffice - I may experiment.

On my main question - can a repaired top-coat satisfactorily be spot re-sprayed - my research so far suggests it can as long as a hard edge to the new spray is avoided and recognising that some buffing/polishing may be required to smooth the old with the new. If anyone has direct experience on this I'd welcome their input.
 

cornucopia

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your research is correct shellac is an excellent sealer- zinnser BIN is shellac based but is also an excellent obliterating primer and adhesion promoting primer and stain block all rolled into one so it takes some beating as a primer but it’s not easiest paint to apply as it dries like lighting and has a strong odour so you might not want to put it in your spray equipment and you might not want to spray with it in a confined space.
an alternative might be Dulux trade's ultra grip primer which is a two pack but is also water based- it won’t seal it as well but has excellent opacity and high adhesion properties for a WB primer.

On your main question I would say no it cant- you would have to re-spray that panel to do a satisfactory repair.

best wish's
George
 
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