Using oil base poly in a Harbor Freight HVLP spray gun kit and spraying questions.

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Forum topic by Tennwood posted 10-22-2010 10:43 PM 11098 views 0 times favorited 6 replies Add to Favorites Watch
View Tennwood's profile


112 posts in 3421 days

10-22-2010 10:43 PM

Topic tags/keywords: spray gun hvlp spray finish water base polyurethane oil base polyurethane finishing

I just purchased a HVLP sprayer from Harbor freight (model 93305). I went low cost as this is the first sprayer I have used, and they were on sale. A couple of Jocks have given pretty favorable reviews on it also. I have two questions about the sprayer and two unrelated spraying questions:

1. Can I use an oil base polyurethane in it? I called Harbor Freight tech support and he said yes, but there was a lot of hesitation in his voice. It was the first time he had this question.

2. Whether I use oil base or water base – do I need to cut the poly, and by how much?

3. I used a MinWax oil based stain, is there any problem using a water based poly over it?

3. If it isn’t windy, can I spray outside or do I need to make myself a makeshift booth?



-- Jim, SE Tennessee, "Don't spare the kindling Dear, we have plenty"

6 replies so far

View CampD's profile


1742 posts in 3726 days

#1 posted 10-23-2010 03:29 AM

Dont know what size tip is in it, but I use a larger one for oil poly and thin it with mineral spirits.
Water based really dosnt need to be thinned.
Always test and set the spray pattern, I practice on a piece of cradboard.
as long as the stain has dried thoughly, should be np.
With oil poly, use as much ventilation as posible.

-- Doug...

View CampD's profile


1742 posts in 3726 days

#2 posted 10-23-2010 07:26 PM

“Heard using mineral spirts can cause cat eyes in the finish”
1st, use only fresh mineral spirts to thin poly, its cheap (I mark the date on the container) (use the older stuff to clean the gun)
2nd, cats eye is most likly water in the air supply from the compressure, you need a water seperator in line anytime you spray an oil or enamal finish!

-- Doug...

View Tennwood's profile


112 posts in 3421 days

#3 posted 10-23-2010 08:15 PM

Thanks for the input.

I bought some water base poly today and will give it a try this week. Being this is the first time around, I decided it was the safest. As I don’t having any experience spraying, I wouldn’t know how much, if at all, to thin with the mineral spirits with the oil base. At $29 a gallon, I really don’t want to be wasting it.

Camp- the sprayer only comes with one tip, so I an going to have to play with it. I have lots of old plywood I can spray with water ‘till I get the hang of it.

-- Jim, SE Tennessee, "Don't spare the kindling Dear, we have plenty"

View CampD's profile


1742 posts in 3726 days

#4 posted 10-23-2010 09:14 PM

I like to use cardboard to set and test the spray pattern.
It darkens when you spray making it easy to see how the gun is set.
nice even color, set good
voids, needs ajusting, good to tell the fan width (spary width)
best of all once it dries, you can use it again.
Most of all, have fun and practice.
Ohh, first coat should be real light only enough to seal the wood, then sand smooth.

-- Doug...

View Gregn's profile


1642 posts in 3224 days

#5 posted 10-23-2010 10:47 PM

Jim, thin about 15% with mineral spirits which isn’t much.

-- I don't make mistakes, I have great learning lessons, Greg

View rusticandy's profile


110 posts in 3770 days

#6 posted 10-24-2010 09:26 PM

Just to warn you- It will be a PITA to clean the sticky mess. You should consider switching to target coatings (water based and VERY sprayable). Easy clean and no fumes.

-- rustic andy

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