Spray equipment and paint

sts9fan · « **on:** 14 Jul 2009, 10:23 pm »

I am currently working on a speaker project that I am going to paint. I think I will buy a cheaper hplv gun as I have a suitable compressor. What should I look for? What size tip is good for smallish woodworking projects? 1mm? 1.2mm?
As for paint I am going to use the zinner bins that for a primer. I want to get a flat finish but am not sure what paint to use. I may want get some custom colors. I want it to be durable and not too hard to work with so no high voc paints that I will need a jump suit for.
Thanks for the suggestions
Kris

TF1216 · « **Reply #1 on:** 14 Jul 2009, 11:56 pm »

Sweet! A few tips that I took away from a diy project are as follows:

1) Treat all MDF edges preventing the primer from soaking into the wood

2) Finding the correct primer is where the game is won. If I were to do my project over I would used a hard primer as a base then a softer primer on top to sand smooth.

3) Plan ahead

I attached a picture of the diy speakers I had help building. Please ignore the mess. I have leftover paint if you are interested. I'll give it to you SUPER cheap.

Christof · « **Reply #2 on:** 15 Jul 2009, 12:35 am »

Kris

I highly recommed you visit Homestead Finishing Products website. Google it. Look at the used, b stock area there are some nice Qualspray guns for very good price. Call homestead and talk with Jeff jewitt....he will set you up based on you budget. All else is a crap shoot.
c.

Scott F. · « **Reply #3 on:** 15 Jul 2009, 02:09 am »

Funny you ask about the HPLV sprayer. Just a day or two ago I was talking to one of the painters at one of my construction projects about this exact subject. He was spraying a clear coat of a type of urethane that we use in wet areas. This area happened to be a dish washing room in a high school.

I noticed he was using the cheapest of the cheap sprayers, a Central Pneumatic from Harbor freight. This particular one was $14.99.

I asked specifically about the type of guns and he said NOT to use a HPLV gun. Reason being is they clog and spit especially when you are trying to do finish coats. He said a traditional gun (high pressure and lots of paint) works the best because it atomizes better.

Then I asked him why the cheap gun? He said because it sprays just as good as his $500 Binks and DeVilbiss sprayers. He even uses it for painting cars it sprays so good.

I know, its counter intuitive buying something so cheap when you are trying to do finish work but after seeing his work on this and about ten other jobs (he is my regular painter), I can certainly attest for the quality of the gun and its finish.....then again, a BIG chunk of it is the fact that the guy holding it knows what hes doing too

Here's the link to the gun (I think this is the right one

).

Cheap gun

I;m planning on picking up a couple myself since they are so cheap...that and I'm getting ready to to move my compressor up to my wood shop so I can start spraying stains and finishes.

Martyn · « **Reply #4 on:** 15 Jul 2009, 06:47 am »

I agree with Christof - talk with Jeff Jewitt. Jeff is an acknowledged expert in wood finishing and will not bullshit you. Check the specs of your compressor first, because whatever you gun get must be matched to that.

Maybe you'll be lucky with a cheap gun; maybe you won't. Frankly, I think life's too short to spend it being frustrated by poorly functioning equipment (especially when it's full of paint)!

sts9fan · « **Reply #5 on:** 15 Jul 2009, 12:39 pm »

Thanks guys, I will call Jeff when I am ready to get the gun. I figure I want one that can change tips for different finishs.
What type of paint have you used on speakers? I want to mix custom colors so I guess I would want a base and tint.

JoshK · « **Reply #6 on:** 15 Jul 2009, 12:57 pm »

Quote from: tf121682 on 14 Jul 2009, 11:56 pm

Sweet! A few tips that I took away from a diy project are as follows:

1) Treat all MDF edges preventing the primer from soaking into the wood

2) Finding the correct primer is where the game is won. If I were to do my project over I would used a hard primer as a base then a softer primer on top to sand smooth.

I can definitely concur with #1. I have been primering my baffles. I put a 1.25" roundover on the edges which makes their edges large. MDF edges soak up paint/primer like no bodies business and also shrink/expand making the edges look poor. The regular face of MDF doesn't do this. So it is imperative that you pretreat the edges if you don't want the seams to show through the paint.

I found out that it takes a lot to treat the edges. The most often suggested treatment is watered down PVA (wood glue) or shellac. I had a lot of extra shellac and have used it before so that is what I used. It took much more than I expected. It keeps soaking it up. Keep putting it on until it doesn't soak it up anymore and then sand smooth. Then you can start to primer/paint.

JoshK · « **Reply #7 on:** 15 Jul 2009, 01:00 pm »

P.S. the other technique sometimes suggested and supposedly what Wilson does is veneer the MDF first before you paint. Maybe something like maple which has small pores. The veneer ensures you have a smooth surface to paint and it keeps the MDF expansion from showing through the finish.

sts9fan · « **Reply #8 on:** 15 Jul 2009, 01:03 pm »

So is a shellac based primer/sealer good enough for the first seal or should I use something specialized?

Did you do the shellac just on the cut ends?
Thanks
Kris

JoshK · « **Reply #9 on:** 15 Jul 2009, 01:10 pm »

I went ahead a sealed the whole thing with shellac. I wanted to make sure when I was sanding the primer, if I sanded through I wouldn't be opening up the treated face of the MDF and making another "edge".

I am not an expert. I have done this on exactly two large baffles. But the baffles have sat for 2 months now and no signs of expansion/shrinkage. The humidity has varied greatly during this time too. So I think I am in the clear. I just used a lot of shellac. I recommend getting the can and a pad and rubbing it on. The spray cans empty too quickly. Shellac sands easily to a very smooth finish and fills in minor imperfections, so too much isn't an issue.

Larger imperfections are better filled with bondo. I am still getting use to using that. It dries a bit too quickly for me, which means you have to constantly mix a tiny bit at a time, which is a pain.

TF1216 · « **Reply #10 on:** 15 Jul 2009, 01:26 pm »

I can offer a couple more suggestions on top the great info JoshK has provided.

Use bondo for large imperfections and use body filler (red in color) for small ones. It is much easier to sand.

Sanding becomes very important when painting so I suggest reading up on that.

I attempted to create a pearl finish on my speakers. We were successful in creating the finish I was after but the flakes/additives in the paint detract from the natural beauty of the color. I ended up going with a high gloss black and a high gloss silver faded to black as seen above. (sorry for the stupidly, large picture) We were trying to replicate what can be seen on some of the Rockport Technology pictures.

sts9fan · « **Reply #11 on:** 15 Jul 2009, 02:05 pm »

cool
I think I have a plan of attack

1) Bondo or surfacing putty all imperfections
2) sand the whole thing down so everything is nice repeat bondo where needed
3) Seal the crap out of it with shellac
4) Prime sand repeat

TF1216 · « **Reply #12 on:** 15 Jul 2009, 02:20 pm »

I would start by treating the edges and flat surfaces if they get scuffed or have any imperfections at all.

I used shipping tape to adhere the baffles to the cabinets during travel. When the tape was pulled off it took with it the wax protecting the MDF. Those areas took hours to fix because we did not treat them with the glue/water mix. I would treat all edges 2 or 3 times while giving the surfaces plenty of time to try between coats.

Be careful of dust as well. It will cause you to bang your head against every hard object you see

Warm weather is your friend imo because it will reduce the dry time for bondo and primer.
Lastly, finding the right primer is key as well as not being cheap on all the sanding equipment you can find.

JoshK · « **Reply #13 on:** 15 Jul 2009, 02:21 pm »

Quote from: tf121682 on 15 Jul 2009, 01:26 pm

Use bondo for large imperfections and use body filler (red in color) for small ones. It is much easier to sand.

Thanks for that! I will have to try body filler. I have some really small imperfections to smooth out and bondo was a pain to use, although it does work well.

JoshK · « **Reply #14 on:** 15 Jul 2009, 02:25 pm »

Also, Jeff Jewitt's tutorial on rubbing shellac is very useful! That is what I followed when I did my amp chassis (in cherry). I also found it is just useful more generally when using shellac although you don't have to be as anal when treating MDF with shellac, but the sanding steps would be relavent I'd think.

TF1216 · « **Reply #15 on:** 15 Jul 2009, 02:29 pm »

I am sorry to keep filling your thread sts9fan. You are a New England guy as well so I hope i get more leeway.

I know if I did not have the help of someone with experience I would not have taken a lot of steps far enough. For example, when sanding I had to had to ask numerous times if the surface was smooth enough. The answer was always "No!". Practicing the entire process on a scrap piece of MDF might be a good idea.

sts9fan · « **Reply #16 on:** 15 Jul 2009, 02:53 pm »

no worries!! This is what I am looking for!

I think I am for sure gonna practice on scrap.

TF1216 · « **Reply #17 on:** 15 Jul 2009, 02:59 pm »

I have some red and blue flake leftover if you want it. I got it for free from Sanel Auto Parts.

i went with products from Sanel Auto Parts except for the silver which my partner had leftover from work he did on a truck.

sts9fan · « **Reply #18 on:** 17 Jul 2009, 12:21 pm »

I may take you up on that blue and red flake.

Ok one more question to clarify. The stupid weather here has taken a turn for the humid and I do not have a climate controlled room to work in. Would it be bad if I 1) sand the whole thing down 2) shallac everything to seal it 3) fill the imperfections with bodo etc then sand and seal again, or should I just go straight to primer after the bondo step.

I am REALLY slow working so I want to stabalize them before I fill stuff that way I can do one cab at a time. Shellac will not screw with filler? Do I need diluted shellac or can I just grab stuff of the shelf?

Kris

JoshK · « **Reply #19 on:** 17 Jul 2009, 01:09 pm »

I wouldn't sand the MDF before you shellac, except for the edges that are already exposed. I used non-diluted Shellac, right off the shelf. If you want, you can dilute it some for finer coats at the end, but I didn't.