The 'Paint booth' discussion - Paint and Finishing questions - Page 4

Ahh, thanks for the info N8. How about my airless...think it could work? if so, what tip would you reccomend?

FWIW, Acry-Tech pretty much recommends against using a HVLP setup unless you're a high volume cabinet shop. link

i don't know about and airless one, I've not tried that. at work I use my 3M primer gun with a 1.8 tip. This is the gun : http://solutions.3m.com/wps/portal/3M/en_EU/BodyshopSolutions/-/Products/NewProducts/?PC_7_RJH9U5230GG880IHA65CELUBU0000000_assetId=1273692243291

I have to admit when 3M brought it out to me, I didn't like the though of a plastic gun with replaceable tips but after using it, you could easily finish your topcoat with it. It's an amazing product. We pay $50 for the gun and the tips are $5 each, though if you clean the tips out, we get 100 uses out of them for primer. Thats the only gun I've ever used with duratex.

Checked out the sprayer and the videos, pretty cool. The price for the sprayer and tips is hard to beat, and as you said, keeping them clean extends the lifespan considerably. I'm just worried about the price at the other end of the system. Anything you would recommend in the $2-300 range that I could use the 3M gun with?

I honestly have no idea whats good in that range. We use giant 20K screw compressors at work and I only have a smaller DV 20 gallon one at home but it was $800.

Thanks again. Ya, that's what separates the pro from the amateur right there. I'll keep my eyes open for a deal and I may have to employ the services of a body shop, but that's the last resort! What's the typical rate vs. buying a hvlp system to diy?

You can get a 60 gallon / 240V compressor. They have plenty of airflow. They're not quite $200-300 new though.

Well, not sure how big the tank is, but the compressor that came with the house "because it was too heavy to move" is a 240v compressor. Would I just need an air regulator and shut off valve between the compressor and gun? S**t...if that's all I need...I'm doing it. Edit: Tank is 3'X1'.

What psi to shoot the spray grade duratex?

Gorilla, sorry to derail, man.

Sweet. Excellent thread title btw.

Pressure is not the problem, volume is. See howany GPM your gun choice requires and look up the specs on the compressor.

HVLPs can outrun most residential compressors. Normally need like >10-15GPM at least for most setups.

Well, you'd want some filtration and moisture removal too. See if you can find CFM ratings printed on the compressor (or Google the make / model number). Make sure they're higher than what the HVLP gun you're planning to use requires.
In my experience it's usually CFM, not GPM. Most 240V compressors can keep up with a small or medium size HVLP. 120V ones can't. My "residential" 240V / 60 gallon compressor can do 13.4CFM @ 40PSI / 11.5CFM @ 90 PSI. That's enough for most HVLP setups I've seen.

So, Duratex (roller grade) on MDF.. I know I need to fill and sand, but do I need to prime MDF first? According to the Duratex website this product is both a primer and a paint. But I know MDF is very porous...

Some higher solid latexes may work, but the safest route to go would be and solvent based primer (Kilz Oil, Problock Oil, BIN, etc). That's not to say

I would be hesitant to try spraying unthinned through an X7. The max tip size on the X7 is a .017 (typical size recommended for architectural paints) I've never airlessly sprayed Duratex but I envision it being similar to spraying Drylok (pain in the ass) Definitely remove all your filters if you do try to spray it

Solvent based primers beneath water based coatings can lead to bubbling unless the primer is totally cured, which can take weeks. Alcohol based primers are generally OK, as they cure rapidly.

I have used this:
http://www.rustoleum.com/CBGProduct.asp?pid=37

With Krylon spray paint with no issues on MDF. Turned out well.

I don't use a primer with DuraTex, it's self priming. I've seen others prime with black latex paint to color the cab so that they don't need to use as much DuraTex. But I only use it on pro-sound cabs, where thicker is better.

Bill, have you used Duratex on MDF without priming?

I would definitely paint the "end grain" of the MDF with something and give it ample time to dry (and don't sand through it afterward) before putting Duratex on MDF.

Like an oil based primer or shillac?

Based on what I read mixing oils with waterborne finishes is not a good idea unless you really give the oils a long time to cure / out gas. Since I know us DIY'ers are impatient a latex primer / paint is probably a better bet.

That makes sense. Thanks. And yes, I am not the most patient person once I get rolling on a project...

I don't use MDF.

I don't usually either... But I am building four 5cu ft enclosures and there is a sale on MDF here... It is about 1/3rd the cost of local Baltic Birch... And I just bought a snow blower since I am tired of shoveling so it ate into my fun budget...

I am going to give my father a call, he is a custom home builder and has a couple of pro painters he has used for 20+ years that might be able to give me some advice as well.

Duratex over bare MDF works fine. There is nothing wrong with using MDF, It's just messy. There are lots that will give reasons both ways but in reality, it makes no difference what you use other than your pocket book and how easy it is to work with. I use both and for anything under 3 CF, I always use MDF, the extra weight is needed over ply in a box that small IMO.

This isn't common nor accurate. Universal primers like the ones I referenced can be topcoated by a number of coatings so long as recoat windows are adhered too. Every single day of the week I spec, spray, roll, and trouble shoot clients on coatings systems. Not a single time has this issue occurred. It is common, however, for people to apply hotter solvent topcoats that blister the prime coat (ie lacquer over alkyd, xylene over alkyd, etc) Slow dry alkyd primer with latex topcoat is a fantastic system, that far exceeds the performance of a latex/latex system when applied to wood.

This advice is no different than any other system. There are quick drying alkyd primers that have 45minute recoats or 24hr recoats. I've been on sites where latex over latex has caused outgassing, which is why the most important aspect is finding a compliant system and following recoat windows.


I will admit that for most a latex over latex system is the most user friendly, but I will forever maintain a slow dry alkyd/latex system is a superior wood finish (although my true love would be a catlyzed lacquer system)

I wouldn't have brought it up if I had not experienced it myself, after the advertised recoat window had passed. Murphy's Law taken into consideration I haven't tempted fate by repeating that experience.

I also use solvent under water then a solvent topcoat. I've done this every day for the last 6 years, 4 to 5 times a day. I've yet to ever have one problem. I'd say Bill you had something else going on. My wood working friends also do the same thing and he said he's also never had a problem.