reducing spi epoxy by 20 percent as a sealer

cllong1

New Member
Does anyone have a schematic or can explain how to reduce epoxy by 20 percent as a sealer, I know this sounds elementary but I have never reduced epoxy or primer by such a percent. All the mixing cups I have only have 10-50% on ratios 2:1 and above and the epoxy is a 1:1 ratio but doesn't have a column for a 10-20 reduction to perform this process. Also when it comes to using a urethane reducer for this can you use any urethane reducer or is any particular mid grade reducer preferred?Thanks in advance
 

Dave C 5

Member
Don’t forget that along with all the mixing scales on your cup there is also an ounce scale. Look at that and do the math . Once you have how much mixed your going to use then turn the cup around and look at how many ounces you have. 1 quart is 32 ounces so 20% of that is about 6.5 ounces
 

cllong1

New Member
Thanks Dave, so it looks like using the 1:1 at 4 will be 16 ounces so 20% of that would be about 3.5 ounces. So, if this sounds about the way to do it I will just use a separate cup to add the ounces in there. Can you or some confirm that I am correct and not assuming, I would hate to have think I mixed it correctly and stuff starts peeling off or not sticking
 

jcclark

Oldtimer
A few percent off either way is not going to make a difference.
Usually 1:1:1 works well for me and is not much different than 20%,
It makes it easy to measure.
 

crashtech

Combo Man
1:1:1 is way different than 20%, imo. Around here, 25% is standard for sealer, which is simply 2:2:1

Some common ratios for epoxy:

5:5:1 = 10%
2:2:1= 25%
1:1:1 = 50%
 

cllong1

New Member
1:1:1 is way different than 20%, imo. Around here, 25% is standard for sealer, which is simply 2:2:1

Some common ratios for epoxy:

5:5:1 = 10%
2:2:1= 25%
1:1:1 = 50%
okay , almost got the complete understanding these cups that I have only have 1:1 only and as far as the spi epoxy it's a1:1 ratio, cool no problem. but where do I find that 25% using this column? remember I'm have never reduced this way before. Can you explain the 2:2:1 as its it relates to the cup, here's a pic of the cups I have.
 

Dave C 5

Member
here's the way I do it......say I've mixed my epoxy 1:1 and I turn the cup around and it says I'm at the 20 ounce mark, 20% of that is 4 ounces. So I add my reducer until it comes up to the 24 ounce mark.....20+4=24. No need to use a separate cup. Actually if the mixing ratio scale is confusing you then just use the ounce scale, may require some math....4ounces + 4ounces + 4 ounces is your 1:1:1 ( I think ? pretty sure).
 
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Dave C 5

Member
the 2:2:1.....say you want 10 ounces total, 4oz +4oz + 2oz.....The "1" is going to be half of what ever the "2" is.......Ha ! it's clear in my mind but I'm sure that last part is confusing as hell the way I worded it. Math is way easier in my head than on paper !
 

cllong1

New Member
the 2:2:1.....say you want 10 ounces total, 4oz +4oz + 2oz.....The "1" is going to be half of what ever the "2" is.......Ha ! it's clear in my mind but I'm sure that last part is confusing as hell the way I worded it. Math is way easier in my head than on paper !
Ok Dave , I got it now I just needed to some to explain it to me this way
 

cllong1

New Member
Dave, you nailed it, I text Barry earlier and he said the exact same way. Use the 1:1, turn cup around to ounce scale x.25 ...add that number to total oz... your right no need for extra cup
 

Brad J.

Oldtimer
I use 20 % reduction and just take my mixed number of ounces multiplied by .2. So 10 oz times .2 is 2 ounces of reducer. 20 oz times .2 is 4 ounces of reducer. Simple math that even I can do in my head will I mix.
 

Chris_Hamilton

Trying to be the best me, I can be
I do like Brad does, but you can express 20% reduction as 5:5:2

If you have trouble mixing something that is expressed as a percentage remeber that the percentage is always based off the cumulative total of the ingredients in front of the percentage. 5 parts epoxy +5 parts activator = 10 parts. 20% of 10 parts is 2 parts. If your mix ratio was 2:1:25% it would be 2 parts + 1 part = 3 parts 25% of 3 parts would be 0.75 parts. Example for that ratio in volume would be 16oz to 8 oz (24oz) 25% of 24oz would be 6 oz. So your mix would be 16oz to 8oz to 6oz (2:1:25%)
 
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cllong1

New Member
Thanks chris & Brad, I just have never reduced Or sprayed epoxy as a sealer. I just needed someone to break it down as everyone has so that I can understand it. Yep ... if you mix this S the wrong way you screwed buddy. You guys have definitely helped me understand what I’m doing. Kudos
 

cllong1

New Member
What’s you all take on polyester primer vs regular 2k over body filler on top of epoxy. I am blocking and filling low spots on front cap of 72 C10. I guess the real question is will 2k primer hold up just as good vs polyester primer and then seal it, with 25% reducer. I just don’t want to spray polyester if I don’t need it, also I would have to buy another guy with bigger tip. I Just want a good solid foundation. I found out the hard way that 2K over bare will crack and lift so I took if off and sprayed epoxy first!
 

Dave C 5

Member
Either way you’re good. If I use polyester I will spray 2k over that as the finishing touch then seal it after final sanding
 

cllong1

New Member
ok, been block sanding bodyfiller got a few more areas, I’m working hard to get the low spots out. So I posted a pic, I plan to block everything smooth, reply epoxy bc I burned thru metal in some areas.then I will shoot 2k, block that and seal in epoxy. IF the weather allows me to. How this sound? Also what sand grit do I need to proceed thru so I don’t have sand scratches
 

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